In Flamingo we made these services capable of running in threading mode, in Gazpacho it is time to change the default so that they run with threading by default.

This also means that while in F we use nova-next CI job to selective run these services in threading mode, we will run them now in all of our jobs in threading. So we need a "legacy" CI job that explicitly switch these services back to eventlet mode. This will be the current hybrid plug job. That is renamed to "alternative-configuration" job.

Acceptance Criteria

• n-api, n-metadata, n-scheduler runs with threading mode by default
• they can be still switched back to eventlet mode
• we still have CI coverage for these services running in both mode. The hybrid-plug job is renamed to "alternative-configuration" job and it explicitly switches these services back to eventlet mode