Add locallog in SignalStrengthController to record critical behaviors

SignalStrengthController does dump client's request if it is not
cleared yet. For request that has been cleared, a locallog can help
us analyzing the historical data.

Bug: 229023354
Test: adb shell dumpsys activity service TelephonyDebugService
Change-Id: I9008a2886f44a591c91e8b2fcffa3d1e07c85e2e