[codegen] 7.12 synchronization (#5580)

Co-authored-by: Mpdreamz <Mpdreamz@users.noreply.github.com>

Author: github-actions[bot]

src/ApiGenerator/RestSpecification/XPack/monitoring.bulk.json

@@ -8,7 +8,7 @@
     "visibility":"public",
     "headers":{
       "accept": [ "application/json"],
-      "content_type": ["application/json"]
+      "content_type": ["application/x-ndjson"]
     },
     "url":{
       "paths":[