BluetoothPhoneState: call clearSignalStrengthUpdateRequest() at the beginning...

BluetoothPhoneState: call clearSignalStrengthUpdateRequest() at the beginning of stopListenForPhoneState() to make sure it's always called.

Resolving issues introduced in aosp/1901910.

Per telecom's comment clearSignalStrengthUpdateRequest() must be called before setSignalStrengthUpdateRequest()

clearSignalStrengthUpdateRequest() is called in stopListenForPhoneState() while
setSignalStrengthUpdateRequest() is called in startListenForPhoneState().

In BluetoothPhoneState we make sure stopListenForPhoneState() is always called before startListenForPhoneState(). However, we may return early for stopListenForPhoneState() and clearSignalStrengthUpdateRequest() won't called.

Bug: 240179714
Test: atest BluetoothInstrumentationTests

Change-Id: I7aefcb9ab74d89d00aca67d807799dca7a12eb3c
Merged-In: I7aefcb9ab74d89d00aca67d807799dca7a12eb3c
(cherry picked from 10ef83fe)