ci: pin E2E tests to Ubuntu 22.04 for Playwright compatibility

[GaryJones]

Summary

Pins the E2E test job to Ubuntu 22.04 instead of ubuntu-latest to resolve Playwright browser dependency warnings.

Problem

ubuntu-latest now resolves to Ubuntu 24.04, which has library version mismatches with Playwright's WebKit dependencies. This causes warnings like:

Host system is missing dependencies to run browsers.
Missing libraries:
    libgtk-4.so.1
    libgraphene-1.0.so.0
    libwoff2dec.so.1.0.2
    ... (many more)

While these are warnings (not errors) and only affect WebKit (not Chromium which we use), they add noise to the CI logs and indicate a fragile setup.

Solution

• Pin the test job to ubuntu-22.04 which has better Playwright compatibility
• Added comment explaining why the pin exists
• Clarified the Playwright installation step name

Reference

• Playwright Issue #32546 - GitHub action fails with missing dependencies on Ubuntu 24.04

Test plan

• CI passes on this PR (proving the fix works)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR pins the E2E test job to Ubuntu 22.04 to resolve Playwright browser dependency warnings that occur on Ubuntu 24.04 (now the default for ubuntu-latest). The change addresses library version mismatches between Ubuntu 24.04 and Playwright's WebKit dependencies, which create noisy CI logs and indicate a fragile test environment.

Key changes:

• Pin test job runner to ubuntu-22.04 for better Playwright compatibility
• Add explanatory comments documenting the OS version pin
• Update Playwright installation step name for clarity