Remove `error_tracking` feature flag

Remove the feature flag error_tracking we introduced for the Sentry MVC if it has been ~"Pick into 11.7" and works as expected.

changed milestone to %11.8

added feature flag + 1 deleted label

mentioned in merge request !24306 (merged)

created merge request !24306 (merged) to address this issue

closed via merge request !24306 (merged)

mentioned in commit d4d4ebad

mentioned in commit 51cae079

added devopsmonitor label