Support enable_commenter for instrument_connection (version 2) (#4267)

* Fix psycopg2 (un)instrument_connection to use weakref, not mutate object

* Changelog

* conditional import for docs types

* Lint

* (v2) enable_commenter for instrument_connection psycopg(2)

* Adjust test trace flags

* Changelog

* SImplify test

* lint

* Simplify

* Fix docs

* Changelog

* Changelog

* Revision