Log only current client data in IME tracing

This change moves from dumping information of all Input Method client
instances to dumping only the current client, which is the one in which
the triggering event happened.

Bug: 154348613
Test: flash a device
      start IME tracing by calling "adb shell ime tracing start"
      end IME tracing by calling "adb shell ime tracing stop"
      pull generated trace files and visualize in Winscope
      or start tracing directly through ADB Connect and visualize traces
Change-Id: I46460d3d08947c7d37a8969a2fed6539f35aaf91