test: Run test-sync.sh repo sync tests on CI
Jean-Philippe's test-sync.sh does an excellent job of testing Shrinkwrap's various repo sync options work as intended. So let's hook it up so the CI runs it automatically as a regression test.
For simplicity, let's call it from within test.py so that we can easily add a junit test result for it, which Gitlab will display.
Signed-off-by: Ryan Roberts ryan.roberts@arm.com