N1QL/COUNT/Plasma Throughput drop due to some indexing changes

N1QL/Count/Plasma throughput performance tests dropped in 7.1.0 (compared to 7.0.3)

http://showfast.sc.couchbase.com/#/timeline/Linux/n1ql/count/Plasma#n1ql_thr_Q20_100M_10K_plasma_ok_avg_query_requests_iris

Q20, Count, Plasma tests:

For not_bounded:
7.1.0-1836 - 3.3K : http://perf.jenkins.couchbase.com/job/iris-multi-client/15985/
7.1.0-1835 - 4.3K : http://perf.jenkins.couchbase.com/job/iris-multi-client/15983/

Changelog:
http://changelog.build.couchbase.com/?product=couchbase-server&fromVersion=7.1.0&fromBuild=1835&toVersion=7.1.0&toBuild=1836&f_asterixdb=off&f_cbas-core=off&f_cbft=off&f_indexing=on&f_plasma=on&f_product-metadata=off&f_sigar=off

html report:
http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_710-1836_access_5eeb&snapshot=iris_710-1835_access_d6e7