Display backup dashboard on Horizon when c-bak is enabled

Currently, when enabling c-bak service, the backup tab will not
be shown on Horizon by default. This patch tells Horizon to
display backup dashboard when c-bak is enabled.

Closes-Bug: 2064496
Change-Id: I06295706e985bac58de2878c6d24c51f3267c205
Signed-off-by: MinhNLH2 <minh.nlh.work@gmail.com>

Author: HoangMinhBK

lib/horizon

@@ -109,6 +109,10 @@ function configure_horizon {
         _horizon_config_set $local_settings "" OPENSTACK_KEYSTONE_MULTIDOMAIN_SUPPORT "True"
     fi
 
+    if is_service_enabled c-bak; then
+        _horizon_config_set $local_settings OPENSTACK_CINDER_FEATURES enable_backup "True"
+    fi
+
     # Create an empty directory that apache uses as docroot
     sudo mkdir -p $HORIZON_DIR/.blackhole