touchpad: hide non-error Gestures library logs

These logs can be extremely verbose, especially the tap-to-click
messages, and they're not particularly useful for triaging bugs. Only
enable them when the touchpad gestures debugging property is set.

Bug: 314743031
Test: use a touchpad, and check no TTC logs appear. Run `adb shell 'stop
      && setprop log.tag.TouchpadInputMapperGestures DEBUG && start'`,
      use a touchpad, and check the TTC logs do appear
Change-Id: I4218fc856080199b974ed7a5746a7acf2283cfaa