Remove exclusive module group to reduce HTTP request fragmentation

Cache groups should only be used when it is worth to have the
module(s) in a separate request. Echo is relatively small and
stable in terms of cache combination, not worth it to force
its modules to be in a separate http request as all other modules.

Change-Id: I198b5664d662c93c593d048efcfaf4aac765a6b9
Merge "Remove exclusive module group to reduce HTTP request fragmentation"