[ML] unmuting bwc tests for #73926 (#74012)

Author: benwtrent

x-pack/qa/rolling-upgrade/src/test/resources/rest-api-spec/test/mixed_cluster/40_ml_datafeed_crud.yml

@@ -1,8 +1,5 @@
 ---
 "Test old cluster datafeed without aggs":
-  - skip:
-      version: "all"
-      reason:  "backport: https://github.com/elastic/elasticsearch/pull/73926"
   - do:
       ml.get_datafeeds:
         datafeed_id: old-cluster-datafeed-without-aggs
@@ -45,9 +42,6 @@
 
 ---
 "Put job and datafeed without aggs in mixed cluster":
-  - skip:
-      version: "all"
-      reason:  "backport: https://github.com/elastic/elasticsearch/pull/73926"
   - do:
       ml.put_job:
         job_id: mixed-cluster-datafeed-job-without-aggs
@@ -92,9 +86,6 @@
 
 ---
 "Put job and datafeed with aggs in mixed cluster":
-  - skip:
-      version: "all"
-      reason:  "backport: https://github.com/elastic/elasticsearch/pull/73926"
   - do:
       ml.put_job:
         job_id: mixed-cluster-datafeed-job-with-aggs

x-pack/qa/rolling-upgrade/src/test/resources/rest-api-spec/test/upgraded_cluster/40_ml_datafeed_crud.yml

@@ -8,9 +8,6 @@ setup:
 
 ---
 "Test old and mixed cluster datafeeds without aggs":
-  - skip:
-      version: "all"
-      reason:  "backport: https://github.com/elastic/elasticsearch/pull/73926"
   - do:
       indices.create:
         index: airline-data
@@ -108,9 +105,6 @@ setup:
 
 ---
 "Test old and mixed cluster datafeeds with aggs":
-  - skip:
-      version: "all"
-      reason:  "backport: https://github.com/elastic/elasticsearch/pull/73926"
   - do:
       indices.create:
         index: airline-data