testing: update bitnami image to bitnamilegacy

Author: mauri870

testing/integration/k8s/testdata/opentelemetry-kube-stack/values.yaml

@@ -17,7 +17,7 @@ cleanupJob:
   enabled: true
   # Image details for the kubectl
   image:
-    repository: bitnami/kubectl
+    repository: bitnamilegacy/kubectl
     tag: latest
     # When digest is set to a non-empty value, images will be pulled by digest (regardless of tag value).
     digest: ""