This option allows to configure Number of times nova or ironic client
should retry on any failed http call.
Default value for this new option is "3".
Conflicts:
neutron/notifiers/ironic.py
neutron/notifiers/nova.py
neutron/tests/unit/notifiers/test_nova.py
Change-Id: I795ee7ca729646be0411a1232bf218015c65010f
Closes-Bug: #1883712
(cherry picked from commit e94511cd25)