Implement ostree-to-bootc image upgrade tests including:

• el94-prel-ostree -> el94-src-bootc
• el94-ym2-ostree -> el94-src-bootc

See this slide for more information

Notes:

• We're not implementing crel-to-src upgrade test in this issue. If we decide to implement this test, it will require additional changes from the CI image build procedures (either ostree or bootc images are currently built in a given job)
• We can only use RHEL 9.4 onwards as the OS for the upgrade tests because `bootc` package is not available on previous OS versions.
• We are not implementing y-2 version upgrade test because MicroShift 4.16 not supported on RHEL 9.4 OS.