Define a pipeline path for quarantine MRs

Consider a path for quarantine MRs which only runs minimal jobs such as static-analysis to validate the change.

From @wlsf82

I just had this discussion with Zeff, and we noticed that when we are simply quarantining a test, lots of jobs still run in the CI pipeline, and probably lots of them are not really needed. Then an idea came to my mind. What if we prefix the branch with quarantine- or quarantine/, and in such cases run only static analysis? This way we would have much quicker feedback when a MR is only quarantining tests. WDYT?