clatd: only wait 15s for SIGTERM during shutdown am: 9c05f75eaa am: 70da5b5a0a

Original change: https://android-review.googlesource.com/c/platform/external/android-clat/+/2535679

Change-Id: Ie352766e04ca9082c10db72ae389f3c3241602af
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>