x/tools/gopls: TestSimultaneousEdits flaking on Kokoro with /gopath/pkg/mod: directory not empty

[findleyr]

Just observed the following flake:
https://source.cloud.google.com/results/invocations/747b77b4-86df-4738-8ebf-9c38009a1fc0/targets/golang%2Ftools%2Fgopls-legacy%2Fpresubmit-114/log

It looks like we may have a race during cleanup of the shared directory.

[gopherbot]

Change https://go.dev/cl/421258 mentions this issue: gopls/internal/regtest/misc: simplify shared edit tests

[findleyr]

I believe this should be resolved now. Tentatively closing.