chore(e2e): adapt e2e-kind.yml for release/1.3.x context

- PR trigger: branches main -> release/1.3.x (so this workflow runs on
  PRs against release/1.3.x).
- Default old_version: v1.1.2 -> v1.2.1 (matches the natural upgrade
  source for release/1.3.x; main targets a different floor).

Leaves notify-e2e.yml's `branches: [main]` filter unchanged — the
moca-e2e hub tracks main only, so this workflow stays a safe no-op on
release/1.3.x by design.

Author: puneet2019

.github/workflows/e2e-kind.yml

@@ -3,16 +3,16 @@ name: E2E Kind Tests
 on:
   pull_request:
     branches:
-      - main
+      - release/1.3.x
   workflow_dispatch:
     inputs:
       old_version:
         description: "Old version tag for upgrade tests (used by hardfork/governance/comprehensive)"
-        default: "v1.1.2"
+        default: "v1.2.1"
         type: string
 
 env:
-  OLD_VERSION: ${{ inputs.old_version || 'v1.1.2' }}
+  OLD_VERSION: ${{ inputs.old_version || 'v1.2.1' }}
   DOCKER_IMAGE: mocachain/moca
   DOCKER_TAG: e2e-local
   CGO_CFLAGS: "-O -D__BLST_PORTABLE__"