x/build: frequent 'no space left on device' flakes on linux-arm builder #35543
They run in a tmpfs and those machines have 2GB of ram only.
Easiest fix to just skip the slow and disk-happy "reboot" test.
But I also have been meaning to look at the $WORKDIR size growth per dist test step, and logging that along with the other metrics.
Perhaps there's opportunity to clean up after some tests.
Fixes golang/go#35543 Change-Id: I2554d6ef8400201f10f5f0f0a45a5bbd53104f95 Reviewed-on: https://go-review.googlesource.com/c/build/+/206799 Reviewed-by: Bryan C. Mills <email@example.com>