Merge branch '52195-backport-removal-of-additionalproperties-false-runners-schema' into 'master'

Remove addtionalProperties in runners schema

Closes #52195

See merge request gitlab-org/gitlab-ce!22105

spec/fixtures/api/schemas/job/runners.json

@@ -8,6 +8,5 @@
     "online": { "type": "boolean" },
     "available": { "type": "boolean" },
     "settings_path": { "type": "string" }
-  },
-  "additionalProperties": false
+  }
 }