Avoid extra snprintf() in dsl_deadlist_merge().

Since we are already iterating the ZAP, we have exact string key to
remove, we do not need to call zap_remove_int() with the int key we
just converted, we can call zap_remove() for the original string.

This should make no functional change, only a micro-optimization.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes openzfs#15056

(cherry picked from commit fdba8cb)

Author: amotin

module/zfs/dsl_deadlist.c

@@ -892,9 +892,9 @@ dsl_deadlist_merge(dsl_deadlist_t *dl, uint64_t obj, dmu_tx_t *tx)
 	for (zap_cursor_init(&zc, dl->dl_os, obj);
 	    (error = zap_cursor_retrieve(&zc, za)) == 0;
 	    zap_cursor_advance(&zc)) {
-		uint64_t mintxg = zfs_strtonum(za->za_name, NULL);
-		dsl_deadlist_insert_bpobj(dl, za->za_first_integer, mintxg, tx);
-		VERIFY0(zap_remove_int(dl->dl_os, obj, mintxg, tx));
+		dsl_deadlist_insert_bpobj(dl, za->za_first_integer,
+		    zfs_strtonum(za->za_name, NULL), tx);
+		VERIFY0(zap_remove(dl->dl_os, obj, za->za_name, tx));
 		if (perror == 0) {
 			dsl_deadlist_prefetch_bpobj(dl, pza->za_first_integer,
 			    zfs_strtonum(pza->za_name, NULL));