Merge branch 'docs-clean-redirects-2022-01-18' into 'master'

Clean up docs redirects - 2022-01-18

See merge request gitlab-org/gitlab!78434

doc/development/testing_guide/ci.md

----
-redirect_to: '../pipelines.md'
-remove_date: '2022-01-12'
----
-
-This file was moved to [another location](../pipelines.md).
-
-<!-- This redirect file can be deleted after <2022-01-12>. -->
-<!-- Before deletion, see: https://docs.gitlab.com/ee/development/documentation/#move-or-rename-a-page -->

doc/security/rack_attack.md

----
-redirect_to: '../user/admin_area/settings/protected_paths.md'
-remove_date: '2022-01-14'
----
-
-This document was moved to [another location](../user/admin_area/settings/protected_paths.md).
-
-<!-- This redirect file can be deleted after <2022-01-14>. -->
-<!-- Before deletion, see: https://docs.gitlab.com/ee/development/documentation/#move-or-rename-a-page -->