Enable cert_expiry config entries (#25624)

* Enable cert_expiry config entries

* add black

* lint fixes

* Rerun black

* Black on json files is a bad idea

* Work on comments

* Forgot the lint

* More comment work

* Correctly set defaults

* More comments

* Add codeowner

* Fix black

* More comments implemented

* Removed the catch

* Add helper.py from cert_expiry to .coveragerc