tgc-revival: remove only instance of tgc_test_ignore_in_asset (#15451)

Author: trodge

mmv1/products/compute/BackendService.yaml

@@ -153,8 +153,6 @@ examples:
     min_version: 'beta'
     vars:
       backend_service_name: 'backend-service'
-    tgc_test_ignore_in_asset:
-      - 'RESOURCE.enableCDN' # It has false value in CAI asset
 parameters:
 properties:
   - name: 'affinityCookieTtlSec'