clang-tidy: Fix all remaining misc-include-cleaner violations

- Remove unused includes
- Add common false positive headers to misc-include-cleaner.IgnoreHeaders
- Add IWYU pragma keep for uncommon false positive headers

src/include/override/linux/sctp.h

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+/* The kernel header depends on <arpa/inet.h> being included. */
+
+#include <arpa/inet.h>
+#include_next <linux/sctp.h>    /* IWYU pragma: export */

src/include/override/sched.h

@@ -4,7 +4,8 @@
 /* sched.h includes linux/sched/types.h since glibc-2.41 (21571ca0d70302909cf72707b2a7736cf12190a0),
  * to make struct sched_attr being defined.
  * Note, this must be included before sched.h, otherwise the headers conflict with each other. */
-#include <linux/sched/types.h>
+#include <linux/sched.h>        /* IWYU pragma: export */
+#include <linux/sched/types.h>  /* IWYU pragma: export */
 
 #include_next <sched.h>         /* IWYU pragma: export */