Change some default values for Rabbit driver

It was observed that for the rabbitmq-server version 3.8.2 default
values during failover of one of the rabbit nodes cause rapid connection
recreation. In some cases it leads to the creation of broken exchanges
and hangs of OpenStack operations. Changing rabbit_retry_interval to 5,
rabbit_retry_backoff to 10 and kombu_reconnect_delay to 5.0 fix an
issue.

This change is Pike-only, Queens is implemented in oslo-templates
formula.

Related-Issue: PROD-34332
Change-Id: I83512688e6bd59e38746bed1aee08a0030e024f2
2 files changed