T6056: Change static-host-mapping shold not restart snmpd

We have several config XML definitions that use the same python3
script system_host-name.py

https://github.com/vyos/vyos-1x/blob/current/interface-definitions/system_name-server.xml.in
https://github.com/vyos/vyos-1x/blob/current/interface-definitions/system_host-name.xml.in
https://github.com/vyos/vyos-1x/blob/current/interface-definitions/system_static-host-mapping.xml.in
https://github.com/vyos/vyos-1x/blob/current/interface-definitions/system_domain-name.xml.in
https://github.com/vyos/vyos-1x/blob/current/interface-definitions/system_domain-search.xml.in

Any change in these scripts calls to restart the service snmpd
The service snmpd should be restarted only if host-name or
domain-name was changed.

It is a good idea to rewrite it to get_config_dict in the future.