Resolve "Follow-up from "Use scoped routes for labels and milestones""

Closes #63177

See merge request gitlab-org/gitlab-ce!29983

Pipeline must be present if "Pipeline must succeed" is set

See merge request gitlab-org/gitlab-ce!29926

Keep empty folders in the tree list

Closes #60860

See merge request gitlab-org/gitlab-ce!29196

Update GitLab Runner Helm Chart to 0.6.0/12.0.0

See merge request gitlab-org/gitlab-ce!29982

When removing the last file from a folder in WebIDE, do not remove the
folder from the view. We keep those to give users possibility to
re-upload files to the same folders.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/60860

The `:` key will no longer exit out of the autocomplete dialog,
allowing auto-completion of labels with colons in them.

When a user sets only_allow_merge_if_pipeline_succeeds, also named
as "Pipeline must succeed" project setting, we require the pipeline
to be present.

This solves race condition issues especially with external CI
providers when a build is triggered externally but no pipelines are
created in GitLab yet.

Document that a head pipeline is expected when using "Pipeline
must succeed" setting. Also explain limitations with the use of
only/except where there may not be any jobs created and the merge
request will not be allowed to be merged.

Also add ::Gitlab::LetsEncrypt.enabled? shortcut
and simplify it a lot