Down-weight fuzz targets that have issue(s) with `Fuzz-Blocker` label

[Dor1s]

Just a random thought, feel free to close. We have some logic in update_fuzz_blocker_label that would add a Fuzz-Blocker label to crashes that happen way too often and block the progress of a particular fuzz target. Can we (or do we) down-weight the targets that have such issues, as they are essentially wasting cycles until fuzz blockers get fixed?

[mbarbella-chromium]

We don't specifically track this based on the presence of Fuzz-Blocker, but looking through that function I suspect most of the targets that have issues with the label should also be getting downweighted for having too high a crash count.

We can tweak the thresholds if necessary if it doesn't seem like these are actually being downweighted, but I think the current behavior is probably reasonable. Feel free to reopen if you think there's more to do here.

[inferno-chromium]

Is 0.7 downweight enough - https://github.com/google/clusterfuzz/blob/master/src/appengine/handlers/cron/fuzzer_weights.py#L123

[mbarbella-chromium]

I think it's probably enough for the current rule, but it might be worth down-weighting more heavily for targets that have been experiencing problems longer. That would help here and in a bunch of the other cases, so I'm going to reopen this to track that work.