exec-util: drop redundant log message in do_spawn()

safe_fork() logs that anyway, hence no need to do this twice.

src/basic/exec-util.c

@@ -82,7 +82,6 @@ static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid) {
                 _exit(EXIT_FAILURE);
         }
 
-        log_debug("Spawned %s as " PID_FMT ".", path, _pid);
         *pid = _pid;
         return 1;
 }