tree-wide: Sort includes

This was done by running a locally built clang-format with
https://github.com/llvm/llvm-project/pull/137617 and
https://github.com/llvm/llvm-project/pull/137840 applied on all .c
and .h files.

src/systemctl/systemctl-util.c

@@ -25,8 +25,8 @@
 #include "reboot-util.h"
 #include "set.h"
 #include "stat-util.h"
-#include "systemctl-util.h"
 #include "systemctl.h"
+#include "systemctl-util.h"
 #include "terminal-util.h"
 #include "verbs.h"