Q2 scan wait latency 25% higher with sdk3 vs sdk2 on default collection + request_plus

For Q2 MOI or Plasma with request_plus only, there is a 20% increase in scan wait latency between SDK2 on default collection and SDK 3 on default or non-default collection. This results in a 20% throughput reduction for the SDK3 tests.

SDK2 - http://perf.jenkins.couchbase.com/job/iris-multi-client/7268/console - 49959.0

Query: 

SELECT * FROM `bucket-1` WHERE email = $1;

Index: 

CREATE INDEX by_email ON `bucket-1`(email); 

Graph: http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_700-4678_access_5d32

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SDK3 - http://perf.jenkins.couchbase.com/job/iris-multi-client/7269/console - 42951.0

Query: 

SELECT * FROM default:`bucket-1`.`_default`.`_default` WHERE email = $1;

Index: 

CREATE INDEX i_default_1 ON default:`bucket-1`.`_default`.`_default`(email) WITH {'defer_build': 'true'}

BUILD INDEX ON default:`bucket-1`.`_default`.`_default`('i_default_1')

Graph: http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_700-4678_access_9687

Due to the stats collection difference when using collections these graphs will not be superimposable. The relevant chart for SDK2 is http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_700-4678_access_5d32#1c37410a50a14510b6c466d89fa9d1d6 and the relevant chart for SDK3 is http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_700-4678_access_9687#e3f73e578867ab893ea8e551d09537dc