[ML] Remove one more BWC constant (#74126)

This was missed from #74107

Fixes #74122

Author: droberts195

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/config/Job.java

@@ -757,11 +757,7 @@ public Builder(StreamInput in) throws IOException {
             resultsIndexName = in.readOptionalString();
             deleting = in.readBoolean();
             allowLazyOpen = in.readBoolean();
-            if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
-                blocked = new Blocked(in);
-            } else {
-                blocked = Blocked.none();
-            }
+            blocked = new Blocked(in);
         }
 
         public Builder setId(String id) {