ipatests: delete the replica before uninstallation
    
    The test
    test_installation.py::TestInstallWithCA1::test_install_with_bad_ldap_conf
    is uninstalling a replica by calling ipa-server-install --uninstall
    directly, instead of deleting the replica first.
    
    Use tasks.uninstall_replica instead of tasks.uninstall_master
    to perform a proper uninstallation.
    
    Fixes: https://pagure.io/freeipa/issue/8876
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>