Add onboarding dualtor PR checker (#19503)

In this PR, we add a new PR checker called onboarding dualtor. This new PR checker is for onboarding dualtor speific test scripts.

azure-pipelines.yml

@@ -295,6 +295,23 @@ stages:
           MGMT_BRANCH: $(BUILD_BRANCH)
           TEST_SET: onboarding_t1
 
+  - job: onboarding_elastictest_dualtor
+    displayName: "onboarding dualtor testcases by Elastictest - optional"
+    timeoutInMinutes: 240
+    continueOnError: true
+    pool: sonic-ubuntu-1c
+    steps:
+      - template: .azure-pipelines/run-test-elastictest-template.yml@sonic-mgmt
+        parameters:
+          TOPOLOGY: dualtor
+          STOP_ON_FAILURE: "False"
+          RETRY_TIMES: 0
+          MIN_WORKER: $(T0_DUALTOR_INSTANCE_NUM)
+          MAX_WORKER: $(T0_DUALTOR_INSTANCE_NUM)
+          KVM_IMAGE_BRANCH: $(BUILD_BRANCH)
+          MGMT_BRANCH: $(BUILD_BRANCH)
+          TEST_SET: onboarding_dualtor
+
 #  - job: wan_elastictest
 #    displayName: "kvmtest-wan by Elastictest"
 #    pool: sonic-ubuntu-1c