Fix multiple phrase queries in same search

We were merging all the phrase queries into a single one - this is obviously
wrong.

Change-Id: I9599bd20a9f48aabe60e9634ac4d13d8db02ddd2
(cherry picked from commit 5e81a9dfd2b981a2fcfd1dce31715758fcec3b4d)
Merge "Fix multiple phrase queries in same search" into wmf/1.24wmf22