Mute failing ML tests (#68337)

x-pack/plugin/src/test/resources/rest-api-spec/test/ml/explain_data_frame_analytics.yml

@@ -179,6 +179,9 @@
 
 ---
 "Test field_selection given body":
+  - skip:
+      version: "all"
+      reason: "Awaits fix: https://github.com/elastic/elasticsearch/issues/68337"
 
   - do:
       indices.create:
@@ -241,6 +244,9 @@
 
 ---
 "Test field_selection given job":
+  - skip:
+      version: "all"
+      reason: "Awaits fix: https://github.com/elastic/elasticsearch/issues/68337"
 
   - do:
       indices.create: