Make users API cache mode public if blockinfo is not queried

Blockinfo is currently the only piece of information
(apart from tokens) in the users API which might change
depending on the permissions of the user making the
query. There is no point in making the API request
uncacheable if blockinfo is not requested.

Change-Id: I533f622b7d9077589f148fbb6de98b15ef1c212a
Merge "Make users API cache mode public if blockinfo is not queried"