The Coverity scan app can't handle GCC 11 yet, and will complain about
things inside the stdlib headers and only compile 15 files. So we need
to switch back to Fedora 33 and use GCC 10 instead.
* Try bumping Coverity up now that we should be on a newer version
of it (so hopefully it supports GCC versions with 2 digits in their
number).
* Allow the metadata test to fail because of an upstream bug in the
appdata validation program that thinks the description tag isn't
translated even though it is.
* Don't run the Ubuntu job on schedules
* Fix Coverity job by being explicit it is for schedules only
* Separate the caches for the Ubuntu and Fedora jobs
The original test didn't work if the tgz was not already in the
runner cache. This new test will fail the check if the file is missing
instead of erroring the command.
Ian McInerney
Mark Roszko