llvm packaged versions are never cleaned up

[abadams]

I just had to log in to all the build bots and delete old llvm packaged versions to free up space. There is a pass for cleaning them up, but it doesn't seem to be working.

Also, for posterity: On the mac m1 buildbot more than half the drive was purgeable space that the OS wasn't adequately purging, resulting in out-of-space errors in CI, so I had to leave a bash loop running for a few hours making 1gb files to prod the OS into reclaiming space.

[alexreinking]

Regarding the "posterity" comment - @shoaibkamil said this was a known bug in certain versions of macOS. IIRC that buildbot is running 10.14 (!!). It's badly in need of an OS upgrade.

[abadams]

It's on Sonoma (14, not 10.14), so it's pretty up to date.

[alexreinking]

It's on Sonoma (14, not 10.14), so it's pretty up to date.

Oops, I read that wrong, then. Still, we should update it to 15.