kernel/selinux-testsuite: update the XFS quota bug workaround
    
    The bugfix has been backported in RHEL-8.4, so we can now replace this
    with a kernel version check, increasing the coverage on RHEL-8.4 and
    above.
    
    Verified that the testsuite still passes on RHEL-8.3, 8.4, and RHEL-9.
    
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>