stash: remove merge-recursive.h include

stash was modified to use merge_ort_nonrecursive() instead of
merge_recursive_generic() back in commit 874cf2a (stash: apply
stash using 'merge_ort_nonrecursive()', 2022-05-10).  That makes the
inclusion of merge-recursive.h unnecessary.  In preparation for the
removal of merge-recursive.h, remove the unnecessary include.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: newren

builtin/stash.c

@@ -13,7 +13,6 @@
 #include "lockfile.h"
 #include "cache-tree.h"
 #include "unpack-trees.h"
-#include "merge-recursive.h"
 #include "merge-ort-wrappers.h"
 #include "strvec.h"
 #include "run-command.h"