Proper check for empty response in autoscaling test

searching for literal "[]" string to check for no entities in response
is brittle, as the returned JSON of entities may include empty list
as a value for some properties.

Instead, use proper json path search and comparison.

Related-Issue: PRODX-54144
Change-Id: I85b89b748d663fd1f71fb96055066cae7f42879f
diff --git a/telemetry_tempest_plugin/scenario/telemetry_integration_gabbits/autoscaling_smoke.yaml b/telemetry_tempest_plugin/scenario/telemetry_integration_gabbits/autoscaling_smoke.yaml
index 0cbfd7e..2868b8b 100644
--- a/telemetry_tempest_plugin/scenario/telemetry_integration_gabbits/autoscaling_smoke.yaml
+++ b/telemetry_tempest_plugin/scenario/telemetry_integration_gabbits/autoscaling_smoke.yaml
@@ -7,15 +7,15 @@
       desc: Lists alarms, none yet exist
       url: $ENVIRON['AODH_SERVICE_URL']/v2/alarms
       method: GET
-      response_strings:
-          - "[]"
+      response_json_paths:
+        $: []
 
     - name: list servers none
       desc: List servers, none yet exists
       url: $ENVIRON['NOVA_SERVICE_URL']/servers
       method: GET
-      response_strings:
-          - "[]"
+      response_json_paths:
+          $.servers: []
 
     - name: create stack
       desc: Create an autoscaling stack
@@ -142,12 +142,12 @@
       desc: List alarms, no more exist
       url: $ENVIRON['AODH_SERVICE_URL']/v2/alarms
       method: GET
-      response_strings:
-          - "[]"
+      response_json_paths:
+          $:  []
 
     - name: list servers deleted
       desc: List servers, no more exists
       url: $ENVIRON['NOVA_SERVICE_URL']/servers
       method: GET
-      response_strings:
-          - "[]"
+      response_json_paths:
+          $.servers: []