audio: Reduce the interval between BT proxy registration retries

A follow-up for aosp/2929441. The interval between retries
of connecting to BT proxy must be reduced significantly.
Otherwise, in situations when the BT is not connected
(that happens during tests), the resulting long delay causes
failures at the frameowork level due to resulting long
timeout.

Bug: 322820830
Test: atest audiosystem_tests --iterations 100
Change-Id: Idd84cb22b28d109151f98bb5883dca18a9ae928d