Remove 3 unused movepage messages

Follows-up r4134 (751a0a35f26b):
* movedto

Follows-up r24618 (877d2bac2f0b):
* movenologin

Follows-up r35213 (c75649cf5a10):
* talkexists

Change-Id: I1db90a202f3cb0d93cecd10f6e60874d5478e50a
Merge "Remove 3 unused movepage messages"