Android jobs take a long time to run due to timeouts

[jgraham]

I just had to bump the number of Firefox android jobs testharness jobs to 30 due to timeouts.

With the 4x timeout multiplier, we're waiting 40s for most tests to timeout, and 240s for timeout=long tests. I found one job with a 2hr 10 minute runtime with 37 tests timing out collectively accounting for 50 minutes of that runtime.

This obviously isn't ideal from an efficiency point of view. In m-c we end up with some dubious hacks to avoid these long timeouts, but they don't easily apply in the case we don't know which tests expect to timeout.