CLD-5783 Implement rolling upgrade tests (#27842)

* Make server.prepare idempotent, don't cleanup containers on server.start
* Implement rolling upgrade E2E tests
* Apply Akis' suggestions from code review
* Apply Saturn's suggestions from review
* Communicate RollingRelease on GHA and test automation results channel
* Implement E2E test case versioning for rolling release tests

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Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Akis Maziotis <akis.maziotis@mattermost.com>

e2e-tests/.ci/report.publish.sh

@@ -35,6 +35,7 @@ export BUILD_TAG="${SERVER_IMAGE##*/}"
 export MM_DOCKER_IMAGE="${BUILD_TAG%%:*}" # NB: the 'mattermostdevelopment/' prefix is assumed
 export MM_DOCKER_TAG="${BUILD_TAG##*:}"
 export SERVER_TYPE="${SERVER}"
+export AUTOMATION_DASHBOARD_FRONTEND_URL="${AUTOMATION_DASHBOARD_URL:+${AUTOMATION_DASHBOARD_URL%%/api}}"
 
 if [ -n "${TM4J_API_KEY:-}" ]; then
   # Set additional variables required for Zephyr reporting