Improve headset media button logging in Telecom.

Improve logs when media button presses are raised to Telecom.  We've seen
some issues with this behavior and are hampered by the log level of this
code being debug-only.

Test: Manual testing to verify log presence
Bug: 377845864
Flag: NONE logs only change
Change-Id: Ib2177f2c01686e9400f0dd93afee214bb6d3c852