Many tests skip tests for various reasons but not in a consistent way and
don't always clean up, so add that and switch the tests that do that over.
OpenBSD-Regress-ID: 72d2ec90a3ee8849486956a808811734281af735
Specify host key algorithms in sshd's default set for the SSHFP test,
from djm@. Make the reason for when the test is skipped a bit clearer.
OpenBSD-Regress-ID: 4f923dfc761480d5411de17ea6f0b30de3e32cea