oeqa: runtime: weston: Remove tear down method

oeqa: runtime: weston: Remove tear down method

Tear down method is executed even when the tests are disabled. This lead
to SSH being used to run commands on the target, and as it might fail
when no SSH server is present, we had to use ignore_ssh_fails=True here.

Instead, remove log file just before it is created: it will remain on
the target after the test is run, but this should be acceptable.

Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>