Merge branch 'psk-change-default-data-category-to-optional' into 'master'

Change default metric definition template category to Optional

See merge request gitlab-org/gitlab!66076

generator_templates/usage_metric_definition/metric_definition.yml

@@ -11,7 +11,7 @@ milestone: "<%= milestone %>"
 introduced_by_url:
 time_frame: <%= time_frame %>
 data_source:
-data_category: Operational
+data_category: Optional
 distribution:
 <%= distribution %>
 tier: