Mute failed 120_api_key_auth test till #59425 is addressed.

Author: ywangd

x-pack/qa/rolling-upgrade/src/test/resources/rest-api-spec/test/mixed_cluster/120_api_key_auth.yml

@@ -3,7 +3,7 @@
 
   - skip:
       features: headers
-      version: " 7.5.0 - "
+      version: "all"
       reason: "API key realm name is in metadata since v7.5. https://github.com/elastic/elasticsearch/issues/59425"
 
   - do: