GameSpace: Fix stopping session service in secondary users

Using a static variable to know if a service is running
or not creates race condition in secondary users and
so the game bar (floating action) is not getting closed
until reboot.

Hence, do check if service is running or not in a proper way.

Change-Id: Ic41b719acdd16dd07cc34bb5fdf631059e4dcf50
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>