Add a flag for max_idle postgres connections

Created by: rafax

Add a flag that allows us to tune maximum number of idle Postgres connections (instead of setting it to the maximum size of connection pool).

Test plan

• Tested locally
• Doesn't change the default behaviour

Created by: danieldides

Review: Approved

Created by: michaellzc

Review: Approved

lgtm

Created by: daxmc99

Review: Approved

LGTM should we create an issue to track rollout of this and see if it improves idle connection usage?

Merged by: rafax at 2022-08-23 16:22:27 UTC