chore(cpex): disable (#3670)

* chore(cpex): disable

* chore(cpex): disable cpex tab as well

Author: ravern

website/src/featureFlags.ts

@@ -8,6 +8,6 @@
 export const enableShortUrl = false;
 
 /** Enable Course Planning Exercise */
-export const enableCPEx = true;
+export const enableCPEx = false;
 
-export const showCPExTab = true;
+export const showCPExTab = false;