oeqa/selftest/tinfoil: Improve tinfoil event test debugging

oeqa/selftest/tinfoil: Improve tinfoil event test debugging

We still see occasional test failures for unknown reasons. Add some debugging to
show whether the matching files event was received even if the command complete wasn't.

Also ensure any commandfailed/commandexit event is shown.

This will hopefully aid debugging the next time the issue occurs.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>