CBQE-2431: Remove all references to `all_docs`

The `all_docs` endpoint doesn't exist anymore, hence remove all
references to it.

Change-Id: If5670b87fc6ded377ccb092fac2011e447c69878
Reviewed-on: http://review.couchbase.org/42154
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>