MB-24055: change defaultNumLocks from 193 to 47 (logical no-op).

MB-24055: change defaultNumLocks from 193 to 47 (logical no-op).

Change the value of HashTable::defaultNumLocks from 193 to 47. Note
this is a no-op in a ns_server-controlled configutation as it already
explicilty sets the number of ht_locks to 47; therefore the only time
193 is used is in unit tests.

The reason for changing to 47 is to simplify testing - (1) we should
ideally test in a configuration as close to the "full" system, and (2)
we actually need to reduce the number of locks to <64 so we can run
successfully under ThreadSanitizer.

Change-Id: I1bcecc86cc90fbac215b8ee231179bee5d8cca32
Reviewed-on: http://review.couchbase.org/77889
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: James Harrison <james.harrison@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>