CloudWatch: fix variable query tag migration (#48587)

public/app/plugins/datasource/cloudwatch/migration.test.ts

@@ -223,6 +223,15 @@ describe('migration', () => {
           expect(query.dimensionFilters).toBe('{"InstanceId":"$instance_id"}');
         });
       });
+      describe('when resource_arns query is used', () => {
+        it('should parse the query', () => {
+          const query = migrateVariableQuery('resource_arns(us-east-1,rds:db,{"environment":["$environment"]})');
+          expect(query.queryType).toBe(VariableQueryType.ResourceArns);
+          expect(query.region).toBe('us-east-1');
+          expect(query.resourceType).toBe('rds:db');
+          expect(query.tags).toBe('{"environment":["$environment"]}');
+        });
+      });
     });
   });
 });

public/app/plugins/datasource/cloudwatch/migrations.ts

@@ -149,7 +149,7 @@ export function migrateVariableQuery(rawQuery: string | VariableQuery): Variable
     newQuery.queryType = VariableQueryType.ResourceArns;
     newQuery.region = resourceARNsQuery[1];
     newQuery.resourceType = resourceARNsQuery[2];
-    newQuery.tags = JSON.parse(resourceARNsQuery[3]) || '';
+    newQuery.tags = resourceARNsQuery[3] || '';
     return newQuery;
   }