Enable experimental Cache API in www TestRenderer (#22554)

Author: josephsavona

packages/shared/forks/ReactFeatureFlags.testing.www.js

@@ -23,7 +23,7 @@ export const enableUpdaterTracking = false;
 export const enableSuspenseServerRenderer = true;
 export const enableSelectiveHydration = true;
 export const enableLazyElements = false;
-export const enableCache = false;
+export const enableCache = true;
 export const disableJavaScriptURLs = true;
 export const disableInputAttributeSyncing = false;
 export const enableSchedulerDebugging = false;