Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/33594

Was supposedly fixed in MR for
https://gitlab.com/gitlab-org/gitlab-ce/issues/32086 but seeing this pop
up again

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/33598

Closes #33184

Backport Fix locked milestone in boards being remove-able.
See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1963

Fix https://gitlab.com/gitlab-org/gitlab-ee/issues/2433

Conflicts:
	app/assets/javascripts/boards/boards_bundle.js
	app/assets/javascripts/boards/filtered_search_boards.js
	app/assets/javascripts/filtered_search/filtered_search_manager.js
	spec/features/boards/boards_spec.rb

Single commit squash of all changes for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10878

It's needed due to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10777 being merged with squash.

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/31271

When the dropdown items are too wide, constrain the dropdown to the
offsetParent. Otherwise, let it naturally flow as Select2 wants.

Fix
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10602#note_27871752

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30637

Closes #31095

This table shows the percentage of users who registered in the last
twelve months, who last signed in during or later than each of those
twelve months, by month.

It is only enabled when the usage ping is enabled, and the page also
shows pretty-printed usage ping data.

The cohorts table is generated in Ruby from some basic SQL queries,
because performing the gap-filling and running sums needed in both MySQL
and Postgres is painful.

CE port of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/735