fd-util: rename CLOSE_AND_REPLACE() -> close_and_replace()

We have free_and_replace() and friends, they are all named with lower
letters, even they are macros, not functions.
For consistency, let's rename CLOSE_AND_REPLACE() with lower letters.

This also mekes the macro used more places.

src/core/execute.c

@@ -4073,7 +4073,7 @@ static int add_shifted_fd(int *fds, size_t fds_size, size_t *n_fds, int fd, int
                 if (r < 0)
                         return -errno;
 
-                CLOSE_AND_REPLACE(fd, r);
+                close_and_replace(fd, r);
         }
 
         *ret_fd = fds[*n_fds] = fd;