Drop FC26 support from STDCI
Since Fedora 26 had gone EOL, we should drop support for it in the CI system.
The main motivation for this is to clear the FC26 mirrors which take up ~134G
Things we need to take care of before being able to remove the mirros:
Remove all FC26 slaves
Remove all FC26 jobs
Remove FC26 support from mock_runner.sh
patch merged. no more fc26 jobs.
Blocking this ticket on and as we should remove the older distros before removing FC26
Query for fc26 jobs in jenkins:
Currently it shows there are not many left:
So essentially those are all infra projects and can be moved easily. Specifically for fabric-ovirt, it should probably be switched to STDCI V2 in the process.