[OpenDaylight TSC] Neon EOL - purge jobs on releng/builder.
OpenDaylight Magnesium is released which makes Neon support EOL-ed official. The below CR removes all the Neon jobs from ODL releng/builder repo and infra:
Once the change is merged 'stable/neon' branch will be locked.
Please add this to the next TSC agenda, if we need to take a vote.