Scoped labels with milestone placeholder

Problem to solve

Every release we created a new regression label manually:

This is unnecessary work as the pattern always stays the same.

Intended users

Mainly developers and their managers.

Proposal

Create a magical scoped label regression::$milestone that behaves as if we would create all those labels but automagically fills in the milestone names.

Links / references

similar to https://gitlab.com/gitlab-org/gitlab-ee/issues/2504