tree-wide: Clean up includes

This removes more unused includes from the components already cleaned
up in #37467 and #37457.

Split out of #37344.

src/integritysetup/integritysetup-generator.c

@@ -1,8 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include <stdlib.h>
-#include <sys/stat.h>
-#include <unistd.h>
 
 #include "alloc-util.h"
 #include "fd-util.h"