Inactivity probe needs to be tuned in some deployments to avoid
frequent disconnection between neutron and OVN DBs. Expose parameters
to tune the option for NB DB and SB DB.
Note that configuring inactivity probe requires that connections are
explicitly set. So now connections are configured regardless of
connection protocol (tcp or ssl).
Change-Id: I88512683c88c403acca67d5d7c839d6fb7354557
7bdc37018d