Merge "clat: slightly increase MAXMTU and add comments" am: 9e9da0f3a5 am: 03dd74e237

Original change: https://android-review.googlesource.com/c/platform/external/android-clat/+/2393652

Change-Id: I1ae13cba0747e94e5ac4feea732b11fa447365dd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>