T5734: OpenVPN check PKI DH name exists if DH configured
Check if DH is configured for OpenVPN but does not exist in the
PKI section
set pki dh dh-correct parameters 'xxxx'
set interfaces openvpn vtun10 tls dh-params 'dh-fake'
File "/usr/libexec/vyos/conf_mode/interfaces_openvpn.py", line 208, in verify_pki
pki_dh = pki['dh'][tls['dh_params']]
~~~~~~~~~^^^^^^^^^^^^^^^^^^
KeyError: 'dh-fake'(cherry picked from commit 95cd743c24c6f7720af87450312fc111649db849)