Merge branch '40418-migrate-existing-data-from-kubernetesservice-to-clusters-platforms-kubernetes' into 'master'

Migrate existing data from KubernetesService to Clusters::Platforms::Kubernetes

Closes #40418

See merge request gitlab-org/gitlab-ce!15589

Upgrade scss-lint to 0.56.0

Closes #41754

See merge request gitlab-org/gitlab-ce!16278

Run background migrations with a minimum interval

Closes #41624

See merge request gitlab-org/gitlab-ce!16230

Resolve "Allow QA tests to run with `CHROME_HEADLESS=false`"

Closes gitlab-qa#149

See merge request gitlab-org/gitlab-ce!16248

Resolve "No Rendering of emoji's in Group-Overview after update"

Closes #40549

See merge request gitlab-org/gitlab-ce!16098

Remove the Commit#tree method

See merge request gitlab-org/gitlab-ce!16236

Remove unused push_code_to_protected_branches

Closes #38056

See merge request gitlab-org/gitlab-ce!16253

Incorporate RemoteService.FetchInternalRemote Gitaly RPC

Closes gitaly#857

See merge request gitlab-org/gitlab-ce!16140

Move invites spinach test to Rspec

See merge request gitlab-org/gitlab-ce!16126

Move explore groups spinach test to RSpec

See merge request gitlab-org/gitlab-ce!16129

Resolve "Add graph value to hover"

Closes #38030

See merge request gitlab-org/gitlab-ce!16261

Fix slash commands dropdown description

See merge request gitlab-org/gitlab-ce!16125

disables the shortcut to the issue boards when issues are disabled

Closes #41244

See merge request gitlab-org/gitlab-ce!16020

Protected branch is now created for default branch on import

Closes #3968

See merge request gitlab-org/gitlab-ce!16198

Opitmize migration process by using both unmanaged_kubernetes_service and kubernetes_service_without_template