Refactoring scylla-ci to be triggered directly from each PR using GitHub action. This will allow us to skip triggering CI when PR commit message was updated (which will save us un-needed CI runs) Also we can remove `Scylla-CI-route` pipeline which route each PR to the proper CI job under the release (GitHub action will do it automatically), to reduce complexity
Fixes: https://scylladb.atlassian.net/browse/PKG-69Closesscylladb/scylladb#26799
