Modify epic usage ping key to organise into separate file

- rename existing epic events

doc/development/usage_ping/dictionary.md

@@ -6416,30 +6416,6 @@ Status: `data_available`
 
 Tiers: `premium`, `ultimate`
 
-### `g_project_management_epic_created_monthly`
-
-Count of MAU creating epics
-
-[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_28d/20210305144719_g_product_planning_epic_created_monthly.yml)
-
-Group: `group::product planning`
-
-Status: `implemented`
-
-Tiers: `premium`, `ultimate`
-
-### `g_project_management_epic_created_weekly`
-
-Count of WAU creating epics
-
-[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_7d/20210305145820_g_product_planning_epic_created_weekly.yml)
-
-Group: `group::product planning`
-
-Status: `implemented`
-
-Tiers: `premium`, `ultimate`
-
 ### `geo_enabled`
 
 Is Geo enabled?
@@ -9812,6 +9788,30 @@ Status: `implemented`
 
 Tiers: `free`, `premium`, `ultimate`
 
+### `redis_hll_counters.epics_usage.g_project_management_epic_created_monthly`
+
+Count of MAU creating epics
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_28d/20210305144719_g_product_planning_epic_created_monthly.yml)
+
+Group: `group::product planning`
+
+Status: `implemented`
+
+Tiers: `premium`, `ultimate`
+
+### `redis_hll_counters.epics_usage.g_project_management_epic_created_weekly`
+
+Count of WAU creating epics
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_7d/20210305145820_g_product_planning_epic_created_weekly.yml)
+
+Group: `group::product planning`
+
+Status: `implemented`
+
+Tiers: `premium`, `ultimate`
+
 ### `redis_hll_counters.ide_edit.g_edit_by_sfe_monthly`
 
 Missing description

ee/config/metrics/counts_28d/20210305144719_g_product_planning_epic_created_monthly.yml

@@ -2,7 +2,7 @@
 # Name of this metric contains g_project_management prefix
 # because we are using the same slot from issue_tracking to
 # allow data aggregation.
-key_path: g_project_management_epic_created_monthly
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_created_monthly
 description: Count of MAU creating epics
 product_section: dev
 product_stage: plan

ee/config/metrics/counts_7d/20210305145820_g_product_planning_epic_created_weekly.yml

@@ -2,7 +2,7 @@
 # Name of this metric contains g_project_management prefix
 # because we are using the same slot from issue_tracking to
 # allow data aggregation.
-key_path: g_project_management_epic_created_weekly
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_created_weekly
 description: Count of WAU creating epics
 product_section: dev
 product_stage: plan

lib/gitlab/usage_data_counters/known_events/common.yml

@@ -444,13 +444,3 @@
   redis_slot: pipeline_authoring
   aggregation: weekly
   feature_flag: usage_data_o_pipeline_authoring_unique_users_pushing_mr_ciconfigfile
-# Epic events
-#
-# We are using the same slot of issue events 'project_management' for
-# epic events to allow data aggregation.
-# More information in: https://gitlab.com/gitlab-org/gitlab/-/issues/322405
-- name: g_project_management_epic_created
-  category: epics_usage
-  redis_slot: project_management
-  aggregation: daily
-  feature_flag: track_epics_activity

lib/gitlab/usage_data_counters/known_events/epic_events.yml

+# Epic events
+#
+# We are using the same slot of issue events 'project_management' for
+# epic events to allow data aggregation.
+# More information in: https://gitlab.com/gitlab-org/gitlab/-/issues/322405
+- name: g_project_management_epic_created
+  category: epics_usage
+  redis_slot: project_management
+  aggregation: daily
+  feature_flag: track_epics_activity