floss: Extend D-Bus timeout duration for powerd

btmangerd uses 2 seconds timeout duration to register with powerd
when it starts up. However, the duration is not enough as powerd
could spend more than 2 seconds at initialization. This leads to
an extra delay for system suspend as btmanagerd couldn't respond
to powerd's suspend imminent events properly.
This patch fixes this issue by aligning the timeout duration of
btmanagerd with other D-Bus clients.

Bug: 254156834
Tag: #floss
Test: manual - suspend / resume on brya
Change-Id: I00d3a5bdaa04a315f8f3f705f924855ed7762349