Refactor HFP AG logging to be unguarded

With the recent addition of a process minimum default log level, the
Android Log framework will now enforce the set log level against the
various log invocations we make in code. We no longer need to guard log
invocations on our own.

Tag: #refactor
Flag: EXEMPT, logging only change
Bug: 315046089
Test: atest BluetoothInstrumentationTests
Change-Id: I2cdc3b013c79152b4cb299416a624d6ea73ac69f