When the gnome test runner executes the tests, the test appear to execute in disk
order. This means it sometimes works and sometimes we see breakage in portal-support-snap
and portal-support-snap-classic.
The issue is that some tests create config files but some don't. If they run
in the wrong order, tests see config files they shouldn't and break.
Fix this by deleting the files after each test run, properly cleaning up after
themselves. The cleanup code is based upon gtestutils.c:rm_rf().
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Test all the snap cases and the unknown sandbox one.
We need to use different test processes as we initialize the portal
type early enough that it can't be changed later.
