Return 404 instead of a 500 error on API status endpoint if Geo tracking DB is not enabled

If the tracking database is not configured, the secondary attempts to read from
the Geo DB but fails spectacularly because the tables don't exist.

changelogs/unreleased-ee/sh-geo-check-for-tracking-db.yml

+---
+title: Return 404 instead of a 500 error on API status endpoint if Geo tracking DB is not enabled
+merge_request:
+author:

lib/api/geo.rb

@@ -35,6 +35,7 @@ module API
       get 'status' do
         authenticate_by_gitlab_geo_node_token!
         require_node_to_be_secondary!
+        require_node_to_have_tracking_db!
 
         present GeoNodeStatus.new, with: Entities::GeoNodeStatus
       end
@@ -105,6 +106,10 @@ module API
       def require_node_to_be_secondary!
         forbidden! 'Geo node is not secondary node.' unless Gitlab::Geo.current_node&.secondary?
       end
+
+      def require_node_to_have_tracking_db!
+        not_found! 'Geo node does not have its tracking database enabled.' unless Gitlab::Geo.configured?
+      end
     end
   end
 end

spec/requests/api/geo_spec.rb

@@ -180,6 +180,14 @@ describe API::Geo, api: true do
         expect(response.status).to eq 200
         expect(response.headers['Content-Type']).to eq('application/json')
       end
+
+      it 'responds with a 404 when the tracking database is disabled' do
+        allow(Gitlab::Geo).to receive(:configured?).and_return(false)
+
+        get api('/geo/status'), nil, request.headers
+
+        expect(response).to have_http_status(404)
+      end
     end
 
     context 'when requesting primary node with valid auth header' do