Alpha builds workflow: tweak release description

Author: michaelklishin

.github/workflows/release-alphas.yaml

@@ -27,4 +27,4 @@ jobs:
             -H "Authorization: Bearer ${{ secrets.RABBITMQCI_BOT_TOKEN }}" \
             -H "X-GitHub-Api-Version: 2022-11-28" \
             https://api.github.com/repos/${{ env.DEV_WORKFLOW_REPOSITORY }}/dispatches \
-            -d '{ "event_type": "new_4.1.x_alpha", "client_payload": {"release_repository": "${{ env.DEV_WORKFLOW_REPOSITORY }}", "release_description": "Built from https://github.com/rabbitmq/rabbitmq-server/commit/${{ github.sha }} at ${{ env.PRERELEASE_TIMESTAMP }}", "prerelease": true, "prerelease_kind": "alpha", "prerelease_identifier": "${{ env.PRERELEASE_IDENTIFIER }}", "release_title": "RabbitMQ 4.1.0-alpha.${{ env.PRERELEASE_IDENTIFIER }} (${{ env.PRERELEASE_TIMESTAMP }})", "base_version": "4.1.0", "release_timestamp": "${{ env.PRERELEASE_TIMESTAMP }}", "release_unix_timestamp": "${{ env.PRERELEASE_UNIX_TIMESTAMP }}" }}'
+            -d '{ "event_type": "new_4.1.x_alpha", "client_payload": {"release_repository": "${{ env.DEV_WORKFLOW_REPOSITORY }}", "release_description": "Commit: https://github.com/rabbitmq/rabbitmq-server/commit/${{ github.sha }}, build started at: ${{ env.PRERELEASE_TIMESTAMP }}", "prerelease": true, "prerelease_kind": "alpha", "prerelease_identifier": "${{ env.PRERELEASE_IDENTIFIER }}", "release_title": "RabbitMQ 4.1.0-alpha.${{ env.PRERELEASE_IDENTIFIER }} (${{ env.PRERELEASE_TIMESTAMP }})", "base_version": "4.1.0", "release_timestamp": "${{ env.PRERELEASE_TIMESTAMP }}", "release_unix_timestamp": "${{ env.PRERELEASE_UNIX_TIMESTAMP }}" }}'