[Backport 8.x] Update integration test automation branches (#2465)

Co-authored-by: Josh Mock <[email protected]>

Author: github-actions[bot]

.buildkite/pipeline.yml

@@ -6,7 +6,7 @@ steps:
     env:
       NODE_VERSION: "{{ matrix.nodejs }}"
       TEST_SUITE: "{{ matrix.suite }}"
-      STACK_VERSION: 8.15.0
+      STACK_VERSION: 8.16.0
     matrix:
       setup:
         suite:

catalog-info.yaml

@@ -42,6 +42,9 @@ spec:
         main:
           branch: "main"
           cronline: "@daily"
+        8_x:
+          branch: "8.x"
+          cronline: "@daily"
         8_14:
-          branch: "8.14"
+          branch: "8.16"
           cronline: "@daily"