[aclark4life]

PYTHON-6149

Follow-up to #3099.

Changes in this PR

• Add a regression test for maxPoolSize=0/None with minPoolSize=5 and for the still-raising maxPoolSize=10, minPoolSize=20 case.
• Fix the max_pool_size docstring: "Cannot be 0" contradicted the pool behavior (maxPoolSize=0 has meant unlimited, asserted by test_max_pool_size_zero); it now says a value of 0 or None means no limit.

Test Plan

DB_IP=… DB_PORT=… pytest test/test_pooling.py -k max_pool_size: 7 passed with the fix; the new test fails against the old guard (max_pool_size is not None).

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is the intention of the code captured in relevant tests?
• If there are new TODOs, has a related JIRA ticket been created?

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Have you checked for spelling & grammar errors?
• Is all relevant documentation (README or docstring) updated?

[aclark4life]

Superseded: changes pushed directly to #3099
(patch-1).