ci: remove duplicate release-3.5 merge rules

we already have generic rules to merge the PR's
in devel and release branches with `automatic merge`
rules. Removing the duplicate release-3.5 rule.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

.mergify.yml

@@ -169,38 +169,6 @@ pull_request_rules:
       backport:
         branches:
           - release-v3.5
-  # automerge backports if CI successfully ran
-  - name: automerge backport release-v3.5
-    conditions:
-      - author=mergify[bot]
-      - base=release-v3.5
-      - label!=DNM
-      - "#approved-reviews-by>=2"
-      - "approved-reviews-by=@ceph/ceph-csi-contributors"
-      - "approved-reviews-by=@ceph/ceph-csi-maintainers"
-      - "#changes-requested-reviews-by=0"
-      - "status-success=codespell"
-      - "status-success=multi-arch-build"
-      - "status-success=go-test"
-      - "status-success=commitlint"
-      - "status-success=golangci-lint"
-      - "status-success=mod-check"
-      - "status-success=lint-extras"
-      - "status-success=ci/centos/mini-e2e-helm/k8s-1.21"
-      - "status-success=ci/centos/mini-e2e-helm/k8s-1.22"
-      - "status-success=ci/centos/mini-e2e-helm/k8s-1.23"
-      - "status-success=ci/centos/mini-e2e/k8s-1.21"
-      - "status-success=ci/centos/mini-e2e/k8s-1.22"
-      - "status-success=ci/centos/mini-e2e/k8s-1.23"
-      - "status-success=ci/centos/k8s-e2e-external-storage/1.21"
-      - "status-success=ci/centos/k8s-e2e-external-storage/1.22"
-      - "status-success=ci/centos/k8s-e2e-external-storage/1.23"
-      - "status-success=ci/centos/upgrade-tests-cephfs"
-      - "status-success=ci/centos/upgrade-tests-rbd"
-      - "status-success=DCO"
-    actions:
-      queue:
-        name: default
   - name: backport patches to release-v3.6 branch
     conditions:
       - base=devel