Show search results when query string contains trailing space

The query expression used to search for a term prefix is the prefix
itself with a '*' character appended to it. However, if query string
contains trailing space, the query expresssion (e.g. "screen *") doesn't
work. So to fix this issue, the unnecessary trailing space should be
removed.

Bug: 35231587
Test: manual - go to search in Settings and enter "screen "

Change-Id: Ifa5d96f5d38ad5454272f140da440b8ff55d5614