Update DB connection pooler config

[misaugstad]

Resolves #3316

Updates the following database connection pooler configs, with the goals of reducing the number of idle connections we hold on to, and reducing the likelihood that a server fails to ever connect to a database after an auto-deploy.

db.default.idleMaxAge=2 minute  # default is 10 minutes
db.default.acquireRetryDelay=5 second  # default is 1 second
db.default.acquireRetryAttempts=42  # default is 10
db.default.minConnectionsPerPartition=4  # default is 5

Testing instructions

1. Make sure the server is running and you've loaded a webpage
2. SSH into db container: make ssh target=db
3. Connect to a db: psql -U sidewalk -d sidewalk
4. Run this command to list open connections

   SELECT datname, SUM(numbackends) AS "num_conn"
   FROM pg_stat_database
   GROUP BY datname
   HAVING SUM(numbackends) > 0;
   

5. If you decrease the idleMaxAge to be just a few seconds and you keep running this query, you can watch how the number of connections increases when you load a page, and then goes back down to minConnectionsPerPartition after idleMaxAge.

The retry configs will be a lot easier to test on the test servers!

Things to check before submitting the PR

• I've written a descriptive PR title.
• I've added/updated comments for large or confusing blocks of code.