Fix IDC file for Apple Magic Trackpad 2 over Bluetooth

When I added the Magic Trackpad 2 configs, the Bluetooth on my
development build was broken. I thought that I'd tested the symlinking
behaviour by making the USB config file a symlink temporarily then
changing it back for the CL, but clearly something went wrong, because
the configuration changes are only being applied when the Magic
Trackpad's connected over USB. Making the two files copies of one
another with a comment to remind us to update both at once is probably
the best solution for now.

Bug: 271251605
Test: connect Magic Trackpad 2 by Bluetooth, check gesture property
      values from dumpsys input
Change-Id: I7687e6116f6c46d5f85e1dadffc0b2e4dff23e1e