CBQE-683: allow magic values query params

Random values will be generated for startkey/endkey.
This is useful when auto query was enabled or for
running queries against non system-test data.

python cbsystest.py run query --cluster default --ddoc ddoc1 --view view1 --queries_per_sec 50 --template default --startkey '$int4' --endkey '$int4'

Change-Id: I80bdfc92e0d2adfd5b043467d80118e658d41427
Reviewed-on: http://review.couchbase.org/25000
Tested-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
CBQE-683: update query support in js test files

Including new smart_query.js test case

Change-Id: I4d4f17d38611686e1bf277a6a42fa1ac19d70d3b
Reviewed-on: http://review.couchbase.org/25022
Reviewed-by: Chisheng Hong <chisheng@couchbase.com>
Tested-by: Tommie McAfee <tommie@couchbase.com>
CBD-792: Change prefix of XDCR keys

- Changing prefix for keys used to
determine xdcr lag
- By doing so, we will be avoiding dumping
timing traces in logs for sentinel keys (those
starting with XDCR_TIMING_)
- New prefix: xdcr_track_

Change-Id: Id2ca4112e8a7aad869edff5dd962cfb23795df42
Reviewed-on: http://review.couchbase.org/25026
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: abhinav dangeti <abhinav.dangeti@gmail.com>