[ML][TEST] Add BWC tests for rules syntax change

Original commit: elastic/x-pack-elasticsearch@805d390417

qa/rolling-upgrade/src/test/resources/rest-api-spec/test/mixed_cluster/30_ml_jobs_crud.yml

@@ -94,3 +94,11 @@ setup:
   - do:
       xpack.ml.close_job:
         job_id: mixed-cluster-job
+
+---
+"Test get job with rules":
+
+  - do:
+      xpack.ml.get_jobs:
+        job_id: old-cluster-job-with-rules
+  - match: { count: 1 }

qa/rolling-upgrade/src/test/resources/rest-api-spec/test/old_cluster/30_ml_jobs_crud.yml

@@ -121,3 +121,77 @@
                 "time_format":"epoch"
             }
           }
+
+---
+"Test job with pre 6.2 rules":
+
+  - skip:
+      version:  "6.2.0 - "
+      reason:   "Rules fields were renamed on 6.2.0"
+
+  - do:
+      xpack.ml.put_job:
+        job_id: old-cluster-job-with-rules
+        body:  >
+          {
+            "analysis_config": {
+              "detectors": [
+                {
+                  "function": "count",
+                  "by_field_name": "country",
+                  "detector_rules": [
+                    {
+                      "rule_action": "filter_results",
+                      "rule_conditions": [
+                        {
+                          "condition_type":"numerical_actual",
+                          "field_name":"country",
+                          "field_value": "uk",
+                          "condition": {"operator":"lt","value":"33.3"}
+                        },
+                        {"type":"categorical", "field_name":"country", "value_filter": "foo"}
+                      ]
+                    }
+                  ]
+                }
+              ]
+            },
+            "data_description" : {}
+          }
+
+---
+"Test job with post 6.2 rules":
+
+  - skip:
+      version:  " - 6.1.99"
+      reason:   "Rules fields were renamed on 6.2.0"
+
+  - do:
+      xpack.ml.put_job:
+        job_id: old-cluster-job-with-rules
+        body:  >
+          {
+            "analysis_config": {
+              "detectors": [
+                {
+                  "function": "count",
+                  "by_field_name": "country",
+                  "rules": [
+                    {
+                      "actions": ["filter_results"],
+                      "conditions": [
+                        {
+                          "type":"numerical_actual",
+                          "field_name":"country",
+                          "field_value": "uk",
+                          "condition": {"operator":"lt","value":"33.3"}
+                        },
+                        {"type":"categorical", "field_name":"country", "filter_id": "foo"}
+                      ]
+                    }
+                  ]
+                }
+              ]
+            },
+            "data_description" : {}
+          }

qa/rolling-upgrade/src/test/resources/rest-api-spec/test/upgraded_cluster/30_ml_jobs_crud.yml

@@ -97,3 +97,27 @@ setup:
         job_id: no-model-memory-limit-job
   - match: { acknowledged: true }
 
+---
+"Test get job with rules":
+
+  - do:
+      xpack.ml.get_jobs:
+        job_id: old-cluster-job-with-rules
+  - match: { count: 1 }
+  - match: {
+      jobs.0.analysis_config.detectors.0.rules: [
+        {
+          "actions": ["filter_results"],
+          "conditions_connective": "or",
+          "conditions": [
+            {
+              "type":"numerical_actual",
+              "field_name":"country",
+              "field_value": "uk",
+              "condition": {"operator":"lt","value":"33.3"}
+            },
+            {"type":"categorical", "field_name":"country", "filter_id": "foo"}
+          ]
+        }
+      ]
+    }