Look for load-balancer endpoints in catalog

Load-Blancer tabs should only be enabled when load-balancer endpoint is registered.
When you enable Octavia only on one region and switch to another region which don't have,
It will show you some infinite Error popup : "Error: Unable to retrieve load balancers."

Story 2008853
Task 42372

Change-Id: I1c69f34d70604db0de1e78e8c32716f8744b9e93

octavia_dashboard/api/rest/lbaasv2.py

@@ -28,6 +28,7 @@ try:
 except ImportError:
     from os_client_config import config as occ
 
+from openstack_dashboard.api import base
 from openstack_dashboard.api import neutron
 from openstack_dashboard.api.rest import urls
 from openstack_dashboard.api.rest import utils as rest_utils
@@ -675,6 +676,10 @@ def add_floating_ip_info(request, loadbalancers):
         lb['floating_ip'] = floating_ip
 
 
+def is_load_balancer_service_enabled(request):
+    return base.is_service_enabled(request, 'load-balancer')
+
+
 @urls.register
 class LoadBalancers(generic.View):
     """API for load balancers.

octavia_dashboard/dashboards/project/load_balancer/panel.py

@@ -13,6 +13,7 @@
 # under the License.
 
 from django.utils.translation import ugettext_lazy as _
+from octavia_dashboard.api.rest import lbaasv2
 
 import horizon
 
@@ -21,3 +22,7 @@ class NGLoadBalancers(horizon.Panel):
     name = _("Load Balancers")
     slug = 'load_balancer'
     permissions = ('openstack.services.load-balancer',)
+
+    def allowed(self, context):
+        request = context['request']
+        return lbaasv2.is_load_balancer_service_enabled(request)