Bug 996: Fixed unstable unit test.

This patch fixes failure of manager.implementation UT caused by
too short event timeout.

Change-Id: I857ba986b41aa682bdfbd21505a0d0898ec59ba2
Signed-off-by: Shigeru Yasuda <s-yasuda@da.jp.nec.com>
(cherry picked from commit 3dec8f7c0ec0bc09a80a568f28815b51f2076721)