Job that creates issue if no open milestone is there

### New feature, improvement proposal

Since we create release notes on Github it's crucial that we have a milestone for each branch a PR is merged into. However I noticed multiple times in the past months that especially after a release no new milestone is created, resulting in comments in PR that the PR can't be associated to a milestone.

I suggest to have a pipeline job for each repository which runs at least once a day (and maybe in addition after a release was made) to check if a new milestone was created. If yes - all fine. If not, create an issue (which also results in a mail send to ML).

No files or tests are named. Start by reviewing the repository's existing GitHub Actions workflows and release-related automation to understand how repositories and milestones are handled. Done means a scheduled job checks for an open milestone and creates an issue when none exists, with the expected notification behavior verified.

Written by the indexing model from the issue text.