Rename queryCount -> queryIndex

queryCount was "the count of queries until now, excluding this one",
which isn't as clear as "queryIndex" (especially in calculations).
queryIndex is a more usual way to name something that starts at 0 and
increases by one with each instance.

Test: atest
Change-Id: Id763decf7d2db7462c296955d6123cb1b14585fe
1 file changed