Issue 45345: Optimize default DB connection pool config

[labkey-jeckels]

Rationale

Reviewing performance data, we're spending a surprising amount of time validating DB connections before using them.

Changes

• Switch from validating DB connections when borrowing from the pool to idle times
• Be more prescriptive for the desired size of the pool - initial and idle

[labkey-stuartm]

#https://github.com/LabKey/syseng-chef-server/pull/400
Mirror changes in chef lk_appserver cookbook

[labkey-adam]

Are the [FATAL: database "bt3" does not exist] bootstrap errors related to your changes?

[labkey-jeckels]

@labkey-adam yes, turns out that specifying an initialSize causes the connection pool to throw a SQLException when initializing due to the lack of a DB, breaking bootstrapping. I've backed out that part of the change, which was less important than the other edits.