feat: enable auto migration based on resource count (#115619)

* feat(unified): migration at startup based on resource count

-- draft

* feat: introduce auto migration enablement for dashboards & folders

* feat: enable auto migration based on threshold

* fix: improve

* fix: pass in the auto migrate per migration definition

* fix: minor

* fix: only use one options

* fix: test

* fix: test

* fix: tests

* fix: simplify configs

* chore: rename

* fix: add integration test

* fix: add integration test

* fix: integration tests

* chore: add comments

* fix: address comment

* fix: address comments

* fix: test and auto migration flow

* fix: test

---------

Co-authored-by: Rafael Paulovic <rafael.paulovic@grafana.com>

pkg/setting/setting_unified_storage_test.go

@@ -43,10 +43,16 @@ func TestCfg_setUnifiedStorageConfig(t *testing.T) {
 				}
 				assert.Equal(t, exists, true, migratedResource)
 
+				expectedThreshold := 0
+				if AutoMigratedUnifiedResources[migratedResource] {
+					expectedThreshold = DefaultAutoMigrationThreshold
+				}
+
 				assert.Equal(t, UnifiedStorageConfig{
 					DualWriterMode:                      5,
 					DualWriterMigrationDataSyncDisabled: true,
 					EnableMigration:                     isEnabled,
+					AutoMigrationThreshold:              expectedThreshold,
 				}, resourceCfg, migratedResource)
 			}
 		}
@@ -71,6 +77,7 @@ func TestCfg_setUnifiedStorageConfig(t *testing.T) {
 			DualWriterPeriodicDataSyncJobEnabled: true,
 			DataSyncerRecordsLimit:               1001,
 			DataSyncerInterval:                   time.Minute * 10,
+			AutoMigrationThreshold:               0,
 		})
 
 		validateMigratedResources(false)