github: Revert to Ubuntu 22.04 (from latest) for cgroup v2 testing

github: Revert to Ubuntu 22.04 (from latest) for cgroup v2 testing

Cgroup v2 testing on Ubuntu 24.04 is throwing the following errors.
Revert to Ubuntu 22.04 until the issue is resolved in the distro.

	/home/runner/work/libcgroup/libcgroup/src/.libs/libcgroup.so.0)
			Test:
	012-cgget-multiple_r_flags2.py - RunError:
		command = ['sudo', 'lxc', 'exec', 'TestLibcg', '--',
	'/home/runner/work/libcgroup/libcgroup/src/tools/cgcreate', '-g',
	'memory:012cgget1']
		ret = 1
		stdout =
		stderr =
	/home/runner/work/libcgroup/libcgroup/src/tools/.libs/cgcreate:
	/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.38' not found
	(required by
	/home/runner/work/libcgroup/libcgroup/src/tools/.libs/cgcreate)
	/home/runner/work/libcgroup/libcgroup/src/tools/.libs/cgcreate:
	/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.38' not found
	(required by
	/home/runner/work/libcgroup/libcgroup/src/.libs/libcgroup.so.0)

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>