update: kill keyboxd to prevent umount issues with matter-chroot

matter-iso/main.sh

@@ -43,9 +43,21 @@ check_retc() {
 
 clean_tmpdir(){
   if [ -d "${tmpdir}" ]; then
+    unset_indent
     info "Cleaning up temp directory"
+    set_indent
+    for d in "${tmpdir}/"*; do
+      if mountpoint -q -- "${d}"; then
+        error "Failed: ${d} is still mounted"
+        unset_indent
+        return 1
+      fi
+    done
     rm -rf "${tmpdir}"
+    success "Completed"
   fi
+  unset_indent
+  return 0
 }
 
 check_iso_vars() {