MB-12537: Remove unused file

Change-Id: Iedb2c97bcd3096eb751b244c0a2e06f9628ff7ac
Reviewed-on: http://review.couchbase.org/42782
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: buildbot <build@couchbase.com>
MB-12537: Remove unused class

The `StatsAggregationDuringMemcachedOps` class isn't used anywhere,
hence it is removed. It is also the only user of the `ResultsHelper`,
hence that one can be removed as well.
Change-Id: I83a1c8dd3dbf32ee3d50eea99a9732884f8eda9d
Reviewed-on: http://review.couchbase.org/42783
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: buildbot <build@couchbase.com>
MB-12537: Couchbase Single Server is no longer supported

There is no need to have an install function to install a no longer
supported product.

Change-Id: I566cbec53f9a6de5bdc40fcb8e3036a5b3e22e9c
Reviewed-on: http://review.couchbase.org/42784
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: buildbot <build@couchbase.com>