correct default signal strength threshold for deviceStateMonitor

default lte signal threshold in DeviceStateMonitor is of out sync
with CarrierConfig. We support 4 boundries not 6 boundries today.

Bug: 110134404
Bug: 119688016
Test: Manual
Merged-In: Ia8e0ef967b8c9d8bd5eae128ce859dfefeaa173f
Change-Id: Ia8e0ef967b8c9d8bd5eae128ce859dfefeaa173f
(cherry picked from commit 3c33c8e6)