[CI] Add schedule run for manual tests

[jptissot]

Run the Functional Tests - all Databases and the Frontend Assets build validation periodically (weekly ?)
Automatically create an issue if the Functional Tests - all Databases fails
Automatically create a PR when the Frontend Assets build validation if there are any changes.

[Piedone]

Both of these now run for PRs and main too, see #15951 and #15735.