Update unittest for remote opertion in scene manager

Update unittest for remote opertion in scene manager

In some cases, unittest would produces unexpected results especially when
creation and deletion of scene objects are repeated in continuous unittests.
This patch fixes this issue.

Change-Id: I0294215e5f2578145b4398808146bee1c8199a73
Signed-off-by: Jihun Ha <jihun.ha@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10451
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: JungYong KIM <jyong2.kim@samsung.com>
Reviewed-by: Madan Lanka <lanka.madan@samsung.com>