Query - Aggregation latency increase between Neo builds 2172 and 2173

[This MB covers the apparent Query Service regression between 7.1.0 builds 2172 and 2173. It has been cloned from MB-50737 that covers the apparent Index Service regression between 7.1.0 builds 2174 and 2175. Original MB was opened by Korrigan Clark but I do not have authority to change the Reporter field.

For the smaller regression between builds 2172 and 2173, there were four deliveries from Query but none from Index; also a few from some other services:

http://changelog.build.couchbase.com/?product=couchbase-server&fromVersion=7.1.0&fromBuild=2172&toVersion=7.1.0&toBuild=2173&f_backup=off&f_cbbs=off&f_indexing=on&f_kv_engine=off&f_magma=off&f_ns_server=off&f_plasma=off&f_product-metadata=off&f_query=on&f_query-ee=on&f_testrunner=off&f_udf-api=off

--Kevin Cherkauer]

Aggregation and window query latency has increased slightly. Build 2172 is the last good build then it seems like there might be two different increases between 2172 and 2175.

90th percentile query latency (ms), AG1, Aggregation query, Plasma, not_bounded, s=1 c=1 i=1

http://showfast.sc.couchbase.com/#/timeline/Linux/n1ql/aggregation/Latency

2172 - http://perf.jenkins.couchbase.com/job/arke/9955/ - 580

2173 - http://perf.jenkins.couchbase.com/job/arke/9956/ - 615

2174 - http://perf.jenkins.couchbase.com/job/arke/9957/ - 610

2175 - http://perf.jenkins.couchbase.com/job/arke/9958/ - 684

Comparison -

2172 -2175: http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=arke_710-2172_access_886e&snapshot=arke_710-2175_access_60cf

http://changelog.build.couchbase.com/?product=couchbase-server&fromVersion=7.1.0&fromBuild=2172&toVersion=7.1.0&toBuild=2175&f_kv_engine=off&f_magma=off&f_ns_server=off&f_product-metadata=off&f_query=on&f_udf-api=off&f_backup=off&f_cbbs=off&f_indexing=off&f_plasma=off&f_query-ee=on&f_testrunner=off