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/userdb/userdbd.c

@@ -4,10 +4,10 @@
 #include <sys/types.h>
 
 #include "daemon-util.h"
-#include "userdbd-manager.h"
 #include "log.h"
 #include "main-func.h"
 #include "signal-util.h"
+#include "userdbd-manager.h"
 
 /* This service offers two Varlink services, both implementing io.systemd.UserDatabase:
  *