perf(upgrade): speeds up migrating remember me codes

The Remember me cookie implementation has been improved by moving codes
to a separate table. This performs that migration in one query.

Fixes #6204
test(groups): page owner is not an entity when running SimpleTest

Fixes #6472
chore(views): check if body_attrs are set before attempting to format them

Clears a log warning, cleans up the code and adds @uses to docs

Fixes #6298
chore(groups): check if handler is set in params before calling it

Clean up error logs results in an unset index
chore(views): only pass body_attrs if they are set

Cleaning up log notices
fix(hooks): remove event handler registration

Removes registration of an event handler that is not used in core, consequently reducing noise on the screen log

Fixes #6410