ci: bump plugin-actions/wait-for-grafana to v1.0.4

[mckn]

What

Bumps the SHA-pinned grafana/plugin-actions/wait-for-grafana action across this repo's workflows to wait-for-grafana/v1.0.4 (686ff64):

• .github/workflows/ci.yml (4 occurrences) — v1.0.1 → v1.0.4
• .github/workflows/playwright.yml — v1.0.3 → v1.0.4
• .github/workflows/playwright-nightly.yml — v1.0.1 → v1.0.4

Why

Keep the monorepo CI on the latest wait-for-grafana. No input/output changes.

🤖 Generated with Claude Code

[github-actions]

Playwright test results

Image Name	Version	Result	Report
grafana-enterprise	nightly	❌	View report
grafana-enterprise	dev-preview-react19	✅
grafana-enterprise	13.0.2	✅
grafana-enterprise	11.0.11	✅
grafana-enterprise	9.3.16	✅
grafana-enterprise	8.5.27	✅

Troubleshooting

404 when clicking on View report

By default, the deploy-report-pages Action deploys reports to the gh-pages branch. However, you need to take an extra step to ensure that GitHub Pages can build and serve the site from this branch. To do so:

1. Go to the Settings tab of your repository.
2. In the left-hand sidebar, click on Pages.
3. Under Source, select Deploy from a branch, then choose the gh-pages branch.

This action needs to be completed manually in order for your GitHub Pages site to be built and accessible from the gh-pages branch. Once configured, GitHub will automatically build and serve the site whenever new reports are deployed.