Don't queue refreshLinks jobs on null edit

Bug 50785: don't queue refreshLinks jobs on null edit or API
action=purge forcelinkupdate=1, since these actions are commonly
performed in order to clear the cache of a single page, and queueing
millions of jobs is not the response the user usually expects.

Change-Id: I2dbb5d21fa6b876adefd6bcfc93a83c5904d8d13
Merge "Don't queue refreshLinks jobs on null edit"