Make LTE signal bar thresholds customizable with carrier configuration

Move config_lteDbmThresholds to KEY_LTE_RSRP_THRESHOLDS_INT_ARRAY
to control the LTE signal bar thresholds by carrier configuration.

Test: manual - Checked that the LTE signal bar thresholds can be
controlled by carrier config.
Test: auto - Confirmed that run
ServiceStateTrackerTest#testSignalStrength and it has no problem.
Bug: 70698348
Change-Id: Ia613663956ff00fbf299dcf69113733eae5a3458
Merged-In: Ia613663956ff00fbf299dcf69113733eae5a3458