qa/suites/upgrade: Fix nautilus-x/parallel upgrade test
Fix an issue in 'upgrade-mon-osd-mds.yaml' under nautilus-x/parallel test.
The 'wait-for-healthy' check should not be performed after all the osds
are upgraded since the 'require-osd-release' warning comes into effect
leading to test failure. This check is delayed until after the
'require-osd-release' flag is set to 'octopus'.