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/network/bpf/sysctl-monitor/sysctl-monitor-skel.h

@@ -7,11 +7,11 @@
  * fine given that LGPL-2.1-or-later downgrades to GPL if needed.
  */
 
-#include "bpf-dlopen.h"
+#include "bpf-dlopen.h"                                 /* IWYU pragma: keep */
 
 /* libbpf is used via dlopen(), so rename symbols */
 #define bpf_object__destroy_skeleton sym_bpf_object__destroy_skeleton
 #define bpf_object__load_skeleton sym_bpf_object__load_skeleton
 #define bpf_object__open_skeleton sym_bpf_object__open_skeleton
 
-#include "bpf/sysctl-monitor/sysctl-monitor.skel.h"
+#include "bpf/sysctl-monitor/sysctl-monitor.skel.h"     /* IWYU pragma: export */

src/network/networkd-resolve-hook.c

@@ -11,7 +11,6 @@
 #include "dns-packet.h"
 #include "dns-question.h"
 #include "dns-rr.h"
-#include "env-util.h"
 #include "errno-util.h"
 #include "fd-util.h"
 #include "networkd-link.h"

src/network/networkd-sysctl.c

@@ -5,6 +5,7 @@
 #include "sd-messages.h"
 
 #include "af-list.h"
+#include "bpf-dlopen.h"
 #include "conf-parser.h"
 #include "alloc-util.h"
 #include "cgroup-util.h"

src/network/test-network.c

@@ -9,7 +9,6 @@
 #include "network-internal.h"
 #include "networkd-manager.h"
 #include "networkd-route-util.h"
-#include "string-util.h"
 #include "strv.h"
 #include "tests.h"