python: Allow tuning the session probe_interval from IDL

python: Allow tuning the session probe_interval from IDL

This patch is adding a new parameter called "probe_interval" to the
constructor of the Idl class. This new parameter will be used to tune
the database connection probing for that IDL session, some users might
want to tune it to be less agressive than the current 5s default in OVS
or even disable it.

Reported-at: https://bugs.launchpad.net/networking-ovn/+bug/1680146
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>
Acked-by: Daniel Alvarez <dalvarez@redhat.com>
Signed-off-by: Russell Bryant <russell@ovn.org>