Fix skip version for 14_alias_to_multiple_indices.yml

The message was slightly changed but only in 7.9+

Relates to #59806

rest-api-spec/src/main/resources/rest-api-spec/test/mget/14_alias_to_multiple_indices.yml

@@ -1,6 +1,8 @@
 ---
 "Multi Get with alias that resolves to multiple indices":
-
+  - skip:
+      version: " - 7.8.99"
+      reason: "message was changed to fix grammar in 7.9"
 
   - do:
       bulk: