tree-wide: Clean up includes

This commit cleans up the includes for all the small tools across
the tree.

A few cases of returning EXIT_SUCCESS are replaced with returning
0 to avoid including <stdlib.h>.

Split out of #37344.

src/socket-activate/socket-activate.c

@@ -15,17 +15,15 @@
 #include "errno-util.h"
 #include "escape.h"
 #include "fd-util.h"
+#include "format-util.h"
 #include "log.h"
-#include "macro.h"
 #include "main-func.h"
 #include "pretty-print.h"
 #include "process-util.h"
-#include "signal-util.h"
 #include "socket-netlink.h"
 #include "socket-util.h"
 #include "string-util.h"
 #include "strv.h"
-#include "terminal-util.h"
 
 static char **arg_listen = NULL;
 static bool arg_accept = false;