Impact of the new feature
WMCore Jenkins

Is your feature request related to a problem? Please describe.
Every now and then we have unit tests flipping between success and failure, so we should just add them to the list of unstable unit tests.

Describe the solution you'd like
Add the following unit tests to the text file containing unstable unit tests:

    WMCore_t.WorkQueue_t.WorkQueue_t.WorkQueueTest:testThrottling changed from success to failure
    WMCore_t.Services_t.Rucio_t.RucioUtils_t.RucioUtilsTest:testWeightedChoice changed from failure to success

such that it does not affect the PR tests outcome.

The text file in question is: https://github.com/dmwm/WMCore/blob/master/test/etc/UnstableTests.txt

Describe alternatives you've considered
None

Additional context
None