Introduce experimental live mode [squashfs] #3924

Job	Run time
Run unit tests in containers (Run unit tests for el9toel10 and common repositories on python 3.12...	1m 14s
Run unit tests in containers (Run unit tests for el9toel10 and common repositories on python 3.9,...	1m 12s
Run unit tests in containers (Run unit tests for el8toel9 and common repositories on python 3.9, ...	1m 28s
Run unit tests in containers (Run unit tests for el8toel9 and common repositories on python 3.6, ...	3m 13s
Run unit tests in containers (Run unit tests for el7toel8 and common repositories on python 3.6, ...	4m 5s
Run unit tests in containers (Run unit tests for el7toel8 and common repositories on python 2.7, ...	5m 17s
	16m 29s

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