Set up PR pipeline for pg upgrade 6X_STABLE

contrib/pg_upgrade/ci/ci.yml

+resource_types:
+  - name: pull-request
+    type: docker-image
+    source:
+      repository: teliaoss/github-pr-resource
+  - name: gcs
+    type: docker-image
+    source:
+      repository: frodenas/gcs-resource
+
 resources:
   - name: gpdb6
     type: git
@@ -11,6 +21,16 @@ resources:
       uri: https://github.com/greenplum-db/gpdb.git
       branch: 5X_STABLE
 
+  - name: gpdb6-pull-request
+    type: pull-request
+    source:
+      repository: greenplum-db/gpdb
+      access_token: ((gpdb-git-access-token))
+      base_branch: "6X_STABLE"
+      ignore_paths:
+        - gpdb-doc/*
+        - README*
+
 jobs:
   - name: end-to-end-test
     plan:
@@ -20,4 +40,14 @@ jobs:
         - get: gpdb5
           trigger: true
       - task: run-test
-        file: gpdb6/contrib/pg_upgrade/ci/run-test.yml
\ No newline at end of file
+        file: gpdb6/contrib/pg_upgrade/ci/run-test.yml
+
+  - name: pull-request-end-to-end-test
+    plan:
+      - aggregate:
+        - get: gpdb6
+          resource: gpdb6-pull-request
+          trigger: true
+        - get: gpdb5
+      - task: run-test
+        file: gpdb6/contrib/pg_upgrade/ci/run-test.yml