MB-100: add rebalance to load_memory test

Change-Id: Ia4e8e36e71487cca22aee5fbf5f3e6b8e68cb3a9
Reviewed-on: http://review.couchbase.org/25150
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>
MB-100: add config for xperf tests on apollo

Change-Id: I6afe0db7514dbb6a9e3065b74ea6b9cb6fb1f9f9
Reviewed-on: http://review.couchbase.org/25151
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>