Update docs redirects 2022-01-18

doc/development/testing_guide/ci.md

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-redirect_to: '../pipelines.md'
-remove_date: '2022-01-12'
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-This file was moved to [another location](../pipelines.md).
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-<!-- 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

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-redirect_to: '../user/admin_area/settings/protected_paths.md'
-remove_date: '2022-01-14'
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-This document was moved to [another location](../user/admin_area/settings/protected_paths.md).
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-<!-- 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 -->