Enable build-in-chunks experiment in canary-config.json (ampproject#30301)

Author: kevinkimball

build-system/global-configs/canary-config.json

@@ -35,5 +35,6 @@
   "version-locking": 1,
   "amp-ad-no-center-css": 0,
   "analytics-chunks": 1,
-  "render-on-idle-fix": 1
+  "render-on-idle-fix": 1,
+  "build-in-chunks": 1
 }