tests: stop tracking tests/gpg/random_seed
test-gpg.t left the random_seed file as modified. That was slightly confusing
... and it was accidentally changed in
ea4996754d91.
The seed is created on demand and there is no reason to track it. There is also
no reason to leak state between test runs so we let the test clean up after
running.
Testing that hghave does not crash when checking features
$ "$TESTDIR/hghave" --test-features 2>/dev/null