fix(ci): run Playwright E2E on GitHub Ubuntu

[WH-2099]

Summary

• Run the Playwright full-stack E2E job on the GitHub Ubuntu 24.04 image.
• Keep the standard Playwright system-dependency installation and the existing 15-minute step bound.
• Avoid the Depot apt mirror that prevented browsers from being installed before any scenario ran.

Evidence

• Depot timed out once at 15 minutes and again at 30 minutes while fetching Ubuntu packages at roughly 22 KB/s.
• Skipping system dependencies installed both browser shells in 7 seconds and the Chromium suite passed, proving the test harness itself is healthy; WebKit then correctly reported its required GTK and GStreamer libraries.
• The GitHub Ubuntu runner provides the supported apt environment without maintaining a repository-owned package list or mirror rewrite.

Validation

• The final diff is one workflow line.
• git diff --check passes.
• Full-Stack E2E CI is the behavioral gate for Chromium and WebKit.

[lyzno1]

We should ask the upstream Depot team for a proper fix, or switch back to the native runner. Increasing the timeout would only mask the underlying issue. Taking 30 minutes to download Playwright is clearly unacceptable.

[hjlarry]

30m also not work...