Remove 5 unused block messages

Follows-up r83786 (78059976086f):
* blockip-title
* ipbreasonotherlist
* ipbotheroption
* ipbotherreason
* cant-block-while-blocked

Change-Id: Ic2bb1261dbc9a1fa46ed551159e8ce8ceff774bf
Merge "Remove 5 unused block messages"