CLD-5835 - Do not use the mattermost-build-webapp image from ECR (#23748)

* Only use mattermostdevelopment images
* Fix docker mirroring workflow
* Reenable insights feature for E2E tests

.github/workflows/docker-push-mirrored.yml

@@ -12,6 +12,8 @@ jobs:
     name: cd/Push mirrored docker images
     runs-on: ubuntu-22.04
     steps:
+      - name: Checkout mattermost project
+        uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
       - name: cd/Login to Docker Hub
         uses: docker/login-action@3da7dc6e2b31f99ef2cb9fb4c50fb0971e0d0139 # v2.1.0
         with: