GATT HANDLE: from build time to runtime config

replace GATT_DEFAULT_START_HANDLE and GATT_LAST_HANDLE with system
properties to allow configuration on wear target. New properties are:
  bluetooth.gatt.default_start_handle.value
  bluetooth.gatt.last_handle.value

Bug: 263323082
Test: Build + manual on watches / no-op for phone
Change-Id: I816766103db26bcfbbf3dd1bfc7544bdb491ea31