Cloudwatch: Fix Unexpected error (#74420)

Fix unexpected error when creating a new cloudwatch datasource.

Involves a fair amount of refactoring, so if this causes unexpected issues related to region fetching we can turn this off with the cloudwatchNewRegionsHandler feature toggle, although we do not predict it will so we are enabling it to default to true and hope to remove it shortly.

pkg/services/featuremgmt/registry.go

@@ -203,6 +203,13 @@ var (
 			FrontendOnly: true,
 			Owner:        awsDatasourcesSquad,
 		},
+		{
+			Name:        "cloudwatchNewRegionsHandler",
+			Description: "Refactor of /regions endpoint, no user-facing changes",
+			Stage:       FeatureStageGeneralAvailability,
+			Expression:  "true", // enabled by default
+			Owner:       awsDatasourcesSquad,
+		},
 		{
 			Name:        "showDashboardValidationWarnings",
 			Description: "Show warnings when dashboards do not validate against the schema",

pkg/services/featuremgmt/toggles_gen.csv

@@ -28,6 +28,7 @@ entityStore,experimental,@grafana/grafana-app-platform-squad,true,false,false,fa
 cloudWatchCrossAccountQuerying,GA,@grafana/aws-datasources,false,false,false,false
 redshiftAsyncQueryDataSupport,GA,@grafana/aws-datasources,false,false,false,false
 athenaAsyncQueryDataSupport,GA,@grafana/aws-datasources,false,false,false,true
+cloudwatchNewRegionsHandler,GA,@grafana/aws-datasources,false,false,false,false
 showDashboardValidationWarnings,experimental,@grafana/dashboards-squad,false,false,false,false
 mysqlAnsiQuotes,experimental,@grafana/backend-platform,false,false,false,false
 accessControlOnCall,preview,@grafana/grafana-authnz-team,false,false,false,false

pkg/services/featuremgmt/toggles_gen.go

@@ -123,6 +123,10 @@ const (
 	// Enable async query data support for Athena
 	FlagAthenaAsyncQueryDataSupport = "athenaAsyncQueryDataSupport"
 
+	// FlagCloudwatchNewRegionsHandler
+	// Refactor of /regions endpoint, no user-facing changes
+	FlagCloudwatchNewRegionsHandler = "cloudwatchNewRegionsHandler"
+
 	// FlagShowDashboardValidationWarnings
 	// Show warnings when dashboards do not validate against the schema
 	FlagShowDashboardValidationWarnings = "showDashboardValidationWarnings"