- add pytest marks 'revert_snapshot' to all required fixtures instead
of reverting the snapshots inside them
- add get_top_fixtures_marks() that extracts all the marks
'revert_snapshot' from the test and it's fixtures, order the marks
in the same way as the fixtures depends on each other,
- in the fixture 'revert_snapshot' try to find the most suitable
snapshot for reverting, from latest to earliest.
- mark 'revert_snapshot' removed from system tests which use fixtures
with the same mark (for example, 'k8s_deployed' mark removed from
system tests where the fixture 'k8scluster' is used as a top fixture)
Change-Id: Iad9e56d96d870aa4204ba23e76a5b4df01d4385b
Co-Authored-By: Dmitry Tyzhnenko <dtyzhnenko@mirantis.com>