ipahbacrule: Fix handing of members with action hbacrule

Changing members (host, hostgroup, hbacsvc, hbacsvcgroup, user, group) with
action hbacrule was not working due to the use of the wrong parameter
prefix. This has been fixed and the old members are removed correctly now.

The test script has been reworked completely to verify the fix.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1787996