ostree: remove redundant AUM testcases

The most of the tests are covered by automatic tests or by other manual tests. Hence remove unneeded manual tests.

Lower priority for manual OTA rollback test since we have an automation counterpair.

We keep both rollback tests for offline and online upgrades to have a check point of our automation -- due complexity of the testing process, automatic test may have errors or false-positive behavior in case if we change the AUM, U-Boot or libostree.

Signed-off-by: Denis Pynkin denis.pynkin@collabora.com