Lint suppression cleanups (#47248)

* Unused pylint suppression cleanups

* Remove outdated pylint bug references

* Add flake8-noqa config and note to run it every now and then

* Add codes to noqa's

* Unused noqa cleanups

homeassistant/components/plex/config_flow.py

@@ -27,7 +27,7 @@ from homeassistant.helpers.aiohttp_client import async_get_clientsession
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.network import get_url
 
-from .const import (  # pylint: disable=unused-import
+from .const import (
     AUTH_CALLBACK_NAME,
     AUTH_CALLBACK_PATH,
     AUTOMATIC_SETUP_STRING,