Preferences class deprecation, step 2

Preferences class deprecation, step 2

Remove all functions that have been hard (or superhard, with exceptions)
deprecated previously. They all had no callers with one exception:
* getTimezoneOptions() is called from 3rd party extention, already broken
  anyway.

Mark the remaining functions for removal in 1.34, where whole class
will become {{db-empty}}. They in principle have no callers already, but
let's follow the proper process and give extension developers a bit more
time.

Change-Id: I0e3e98ed1e6242b6ab7c5f21d71478c392fe89a9