fix ab test export warning (#14739)

Author: Jakeii

ab-testing/index.ts

@@ -1,4 +1,3 @@
-// @ts-ignore - extension is required to import this as a package in DCR
-import { ABTests, activeABtests } from './abTest.ts';
+import { allABTests, activeABtests } from './abTest';
 
-export { ABTests, activeABtests };
+export { allABTests, activeABtests };