VPP add verifications to not allow the user to configure low values for main-heap-size.
To reproduce the bug
```
set system option kernel memory default-hugepage-size '2M'
set system option kernel memory hugepage-size 2M hugepage-count '2048'
set vpp settings interface eth1 driver 'dpdk'
set vpp settings memory default-hugepage-size '2M'
set vpp settings memory main-heap-size '4096M'
set vpp settings unix poll-sleep-usec '222'
set vpp settings memory main-heap-size 53M
commit
set vpp settings memory main-heap-size 52M
commit
```
commit fails:
```
vyos@r14# set vpp settings memory main-heap-size 52M
[edit]
vyos@r14# commit
[ vpp ]
An error occurred: [Errno 2] Cannot connect to VPP API. VPP service will
be restarted with the previous configuration
[[vpp]] failed
Commit failed
```
Logs
```
Aug 06 17:43:19 r14 vpp[29620]: received signal SIGABRT, PC 0x7fae2cf79eec
Aug 06 17:43:19 r14 vpp[29620]: Code: 89 c5 f7 dd 3d 00 f0 ff ff b8 00 00 00 00 0f 47 c5 e9 7a ff
Aug 06 17:43:19 r14 vpp[29620]: #0 0x00007fae2cf79eec pthread_key_delete + 0x14c
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libc.so.6
Aug 06 17:43:19 r14 vpp[29620]: #1 0x00007fae2cf2afb2 gsignal + 0x12
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libc.so.6
Aug 06 17:43:19 r14 vpp[29620]: #2 0x00007fae2cf15472 abort + 0xd3
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libc.so.6
Aug 06 17:43:19 r14 vpp[29620]: #3 0x000055c77bee9e33 os_panic + 0x13
Aug 06 17:43:19 r14 vpp[29620]: from /usr/bin/vpp
Aug 06 17:43:19 r14 vpp[29620]: #4 0x00007fae2d125605 clib_mem_heap_realloc_aligned + 0x1e5
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvppinfra.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #5 0x00007fae2d15e9fd _vec_realloc_internal + 0x8d
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvppinfra.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #6 0x00007fae2d2d3fc5 vl_msg_api_config + 0x2c5
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvlibapi.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #7 0x00007fae2da7ce48 format_bier_bift_id + 0x3378
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvnet.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #8 0x00007fae2d1ab62f vlib_call_init_exit_functions + 0x8f
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvlib.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #9 0x00007fae2e51bba3 vat_builtin_main_init + 0x3c3
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvlibmemory.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #10 0x00007fae2d1af526 vlib_log_init + 0x886
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvlib.so.24.10.0
Aug 06 17:43:19 r14 vpp[29620]: #11 0x00007fae2d1692bc clib_calljmp + 0x18
Aug 06 17:43:19 r14 vpp[29620]: from /lib/x86_64-linux-gnu/libvppinfra.so.24.10.0
Aug 06 17:43:19 r14 systemd[1]: vpp.service: Main process exited, code=killed, status=6/ABRT
Aug 06 17:43:19 r14 systemd[1]: vpp.service: Failed with result 'signal'.
Aug 06 17:43:19 r14 systemd[1]: vpp.service: Triggering OnFailure= dependencies.
Aug 06 17:43:19 r14 systemd[1]: Starting Restart VPP on failure...
Aug 06 17:43:19 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:20 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:20 r14 python3[29623]: Traceback (most recent call last):
Aug 06 17:43:20 r14 python3[29623]: File "/usr/libexec/vyos/reset_section.py", line 116, in <module>
Aug 06 17:43:20 r14 python3[29623]: session.commit()
Aug 06 17:43:20 r14 python3[29623]: File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 305, in commit
Aug 06 17:43:20 r14 python3[29623]: out = self.__run_command([COMMIT])
Aug 06 17:43:20 r14 python3[29623]: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Aug 06 17:43:20 r14 python3[29623]: File "/usr/lib/python3/dist-packages/vyos/configsession.py", line 235, in __run_command
Aug 06 17:43:20 r14 python3[29623]: raise ConfigSessionError(output)
Aug 06 17:43:20 r14 python3[29623]: vyos.configsession.ConfigSessionError: Configuration system temporarily locked due to another commit in progress
Aug 06 17:43:20 r14 systemd[1]: vpp-failure-handler.service: Main process exited, code=exited, status=1/FAILURE
Aug 06 17:43:20 r14 systemd[1]: opt-vyatta-config-tmp-new_config_29623.mount: Deactivated successfully.
Aug 06 17:43:20 r14 systemd[1]: vpp-failure-handler.service: Failed with result 'exit-code'.
Aug 06 17:43:20 r14 systemd[1]: Failed to start Restart VPP on failure.
Aug 06 17:43:20 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:21 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:21 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:22 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:22 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:23 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:23 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:24 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:24 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:25 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:25 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:26 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:26 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:27 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:27 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:28 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:28 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
Aug 06 17:43:29 r14 python3[7237]: VPP API connection timeout: [Errno 111] Connection refused
```
The minimal value that we should allow is `96M` or `128M`