updating val template

Author: Miqueasher

validator/src/main/resources/expected-data-template/python/ec2/default/aws-otel-custom-metrics.mustache

@@ -4,6 +4,9 @@
   metricName: custom_export_counter
   namespace: CWAgent
   dimensions:
+    -
+      name: Service
+      value: {{serviceName}}
     -
       name: deployment.environment.name
       value: ec2:default
@@ -56,6 +59,9 @@
   metricName: test_histogram
   namespace: CWAgent
   dimensions:
+    -
+      name: Service
+      value: {{serviceName}}
     -
       name: deployment.environment.name
       value: ec2:default