Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/40825

Conflicts:
	app/views/layouts/_search.html.haml
	app/views/shared/_outdated_browser.html.haml

(EEP) Support multiple Kubernetes cluster per project

Closes #3734

See merge request gitlab-org/gitlab-ee!3603

Geo: Increase parallelism by scheduling project repositories by shard

Closes #3147

See merge request gitlab-org/gitlab-ee!3606

Docs: refactor Pages index

See merge request gitlab-org/gitlab-ee!3675

Add FDW schema refresh to Geo rake task and refactor some code

See merge request gitlab-org/gitlab-ee!3627

Docs: refactor Pages index

See merge request gitlab-org/gitlab-ce!15411

Docs: add admin index

Closes #4222

See merge request gitlab-org/gitlab-ee!3664

Attach files (including images) to epic description

Closes #3938

See merge request gitlab-org/gitlab-ee!3510

ProtectedBranches API handles per user/group granularity

Closes #4131

See merge request gitlab-org/gitlab-ee!3516

Update push_rules.md

See merge request gitlab-org/gitlab-ee!3660

Support mentioning epics

Closes #3853

See merge request gitlab-org/gitlab-ee!3615

Allows admins to disable mirroring

Closes #3730

See merge request gitlab-org/gitlab-ee!3586

Add unique validation for environment_scope in clusters. Add on_environment scope for clusters. Add tests

Create has_environment_scope for centerlizing env_scope specific process. Pass environment_scope to  deployment_platform method.