x/tools/gopls: TestUseGoWork failure on `darwin-arm64-11`

[bcmills]

greplogs --dashboard -md -l -e 'FAIL: TestUseGoWork' --since=2022-07-08
2022-07-14T21:01:58-db8f89b-aa80228/darwin-arm64-11

I don't see the no package for given file position symptom from #53733 (CC @findleyr); it isn't clear to me whether this failure mode is related.

[findleyr]

I still see only that failure when running greplogs. A lot of code has changed here (for the better!), and I suspect that this is now fixed.

We can reopen if it reoccurs.