Fix `test_webui.test_selinuxusermap`
    
    A previous refactoring of SELinux tests has have a wrong
    assumption about the user field separator within
    ipaSELinuxUserMapOrder. That was '$$', but should be just '$'.
    
    Actually, '.ldif' and '.update' files are passed through
    Python template string substitution:
    
    > $$ is an escape; it is replaced with a single $.
    > $identifier names a substitution placeholder matching
    > a mapping key of "identifier"
    
    This means that the text to be substituted on should not be escaped.
    The wrong ipaSELinuxUserMapOrder previously set will be replaced on
    upgrade.
    
    Fixes: https://pagure.io/freeipa/issue/7996
    Fixes: https://pagure.io/freeipa/issue/8005
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>