This server recently had a common ansible applied, which added a
periodic /tmp cleaner, as is needed on other CI machines to deal with
test tempfile leakage. The setting of $HOME to /tmp means that the go
toolchain in there was regularly getting pruned by the tmp cleaner, but
often incompletely, because it was also in use.
Move HOME to a runner owned directory.
Updates #11248
Signed-off-by: James Tucker <james@tailscale.com>
7e17aeb36b