Update yamato triggers to use expressions. (#3556)

.yamato/com.unity.ml-agents-test.yml

   triggers:
     cancel_old_ci: true
     {% if platform.name == "mac" %}
-    changes:
-      only:
-        - "com.unity.ml-agents/**"
-        - "ml-agents/tests/yamato/**"
-        - ".yamato/com.unity.ml-agents-test.yml"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND
+      (pull_request.changes.any match "com.unity.ml-agents/**" OR
+      pull_request.changes.any match ".yamato/com.unity.ml-agents-test.yml")
     {% endif %}
   {% endfor %}
 {% endfor %}

.yamato/gym-interface-test.yml

     - .yamato/standalone-build-test.yml#test_mac_standalone_{{ editor.version }}
   triggers:
     cancel_old_ci: true
-    changes:
-      only:
-        - "com.unity.ml-agents/**"
-        - "Project/**"
-        - "ml-agents/**"
-        - "ml-agents-envs/**"
-        - ".yamato/gym-interface-test.yml"
-      except:
-        - "*.md"
-        - "com.unity.ml-agents/*.md"
-        - "com.unity.ml-agents/**/*.md"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND 
+      (pull_request.changes.any match "com.unity.ml-agents/**" OR 
+      pull_request.changes.any match "Project/**" OR 
+      pull_request.changes.any match "ml-agents/**" OR 
+      pull_request.changes.any match "ml-agents-envs/**" OR 
+      pull_request.changes.any match "gym-unity/**" OR 
+      pull_request.changes.any match ".yamato/gym-interface-test.yml") AND
+      NOT pull_request.changes.all match "**/*.md"
 {% endfor %}

.yamato/protobuf-generation-test.yml

       git diff -- :/ ":(exclude,top)$CS_PROTO_PATH/*.meta" > artifacts/proto.patch; exit $GIT_ERR; }
   triggers:
     cancel_old_ci: true
-    changes:
-      only:
-        - "protobuf-definitions/**"
-        - ".yamato/protobuf-generation-test.yml"
-      except:
-        - "protobuf-definitions/*.md"
-        - "protobuf-definitions/**/*.md"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND
+      (pull_request.changes.any match "protobuf-definitions/**" OR
+      pull_request.changes.any match ".yamato/protobuf-generation-test.yml") AND
+      NOT pull_request.changes.all match "protobuf-definitions/**/*.md"
   artifacts:
     patch:
       paths:

.yamato/python-ll-api-test.yml

     - .yamato/standalone-build-test.yml#test_mac_standalone_{{ editor.version }}
   triggers:
     cancel_old_ci: true
-    changes:
-      only:
-        - "com.unity.ml-agents/**"
-        - "Project/**"
-        - "ml-agents/**"
-        - "ml-agents-envs/**"
-        - ".yamato/python-ll-api-test.yml"
-      except:
-        - "*.md"
-        - "com.unity.ml-agents/*.md"
-        - "com.unity.ml-agents/**/*.md"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND 
+      (pull_request.changes.any match "com.unity.ml-agents/**" OR 
+      pull_request.changes.any match "Project/**" OR 
+      pull_request.changes.any match "ml-agents/**" OR 
+      pull_request.changes.any match "ml-agents-envs/**" OR 
+      pull_request.changes.any match ".yamato/python-ll-api-test.yml") AND
+      NOT pull_request.changes.all match "**/*.md"
 {% endfor %}

.yamato/standalone-build-test.yml

     - pip install pyyaml
     - python -u -m ml-agents.tests.yamato.standalone_build_tests
     - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Basic/Scenes/Basic.unity
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Bouncer/Scenes/Bouncer.unity 
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity 
+    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Bouncer/Scenes/Bouncer.unity
+    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity
-    changes:
-      only:
-        - "com.unity.ml-agents/**"
-        - "Project/**"
-        - ".yamato/standalone-build-test.yml"
-      except:
-        - "*.md"
-        - "com.unity.ml-agents/*.md"
-        - "com.unity.ml-agents/**/*.md"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND
+      (pull_request.changes.any match "com.unity.ml-agents/**" OR
+      pull_request.changes.any match ".yamato/standalone-build-test.yml") AND
+      NOT pull_request.changes.all match "**/*.md"
   artifacts:
     logs:
       paths:

.yamato/training-int-tests.yml

     - .yamato/standalone-build-test.yml#test_mac_standalone_{{ editor.version }}
   triggers:
     cancel_old_ci: true
-    changes:
-      only:
-        - "com.unity.ml-agents/**"
-        - "Project/**"
-        - "ml-agents/**"
-        - "ml-agents-envs/**"
-        - ".yamato/training-int-tests.yml"
-      except:
-        - "*.md"
-        - "com.unity.ml-agents/*.md"
-        - "com.unity.ml-agents/**/*.md"
+    expression: |
+      (pull_request.target eq "master" OR
+      pull_request.target match "release.+") AND
+      NOT pull_request.draft AND
+      (pull_request.changes.any match "com.unity.ml-agents/**" OR
+      pull_request.changes.any match "Project/**" OR
+      pull_request.changes.any match "ml-agents/**" OR
+      pull_request.changes.any match "ml-agents-envs/**" OR
+      pull_request.changes.any match ".yamato/training-int-tests.yml") AND
+      NOT pull_request.changes.all match "**/*.md"
   artifacts:
     logs:
       paths: