fix(ci): wait for the showcase-runtime rollout before running its tests - #5340

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: amannn/action-semantic-pull-request@0723387faaf9b38adef4775cd42cfd5155ed6017, marocchino/sticky-pull-request-comment@773744901bac0e8cbb5a0dc842800d45e9b2b405. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/