Use bundle dockerfile from repo root

Signed-off-by: Siddhesh Ghadi <sghadi1203@gmail.com>

Author: svghadi

.tekton/openshift-gitops-operator-bundle-pull-request.yaml

@@ -27,7 +27,7 @@ spec:
   - name: image-expires-after
     value: 5d
   - name: dockerfile
-    value: bundle/bundle.Dockerfile
+    value: bundle.Dockerfile
   pipelineSpec:
     description: |
       This pipeline is ideal for building multi-arch container images from a Containerfile while maintaining trust after pipeline customization.