FP4: init: Don't mount TraceFS twice

 * AOSP already mounts TraceFS in system init, so mounting it twice
   causes SEPolicy denials. See the comments in this change.

   https://android-review.googlesource.com/c/platform/system/sepolicy/+/1294195

Change-Id: Ic5d9ac2dbd36e404a93a8d48aa0ea933fd7fa701