gd: stack: use new start/stop timeout properties

Watches take longer to finish downloading firmware when the system
is busy. Sometimes FW download takes more than 3 seconds, GD stack
timeouts should be increased accordingly.
Add two new props bluetooth.gd.start_timeout and
bluetooth.gd.stop_timeout, then these props can be adjusted by targets.

Tag: #stability
Bug: 271859293
Test:
 Run the following script for 3 hours and
 check if there is no BT timeout issues

Script: while true
 do
  adb shell su 0 svc bluetooth enable
  sleep 10
  adb shell su 0 svc bluetooth disable
  sleep 5
 done
Change-Id: Icff5db9d6baf24ccfb0237605a62fc08dbc25816