[ci] Refactor: Use composite actions to simplify github workflows

[etrepum]

Description

Refactors github workflows to use composite actions for some of the boilerplate:

• setup-pnpm: setup node, pnpm, and install dependencies
• setup-playwright: cached install of playwright and any required dependencies (e.g. xvfb on ubunutu)
• setup-playground: cached build of the playground
• get-latest-release: replaces third party action with first party github-script

All of the other workflows have been refactored to use these actions

Other changes:

• The matrix of build jobs is expanded manually so we can start running e2e tests as soon as the platform/prod combination is ready rather than serializing tests to start after all builds
• The close-stale-pr workflows has been removed because it didn't work on PRs from forks for security reasons so it wasn't really ever used
• Unused override-react functionality has been removed
• e2e test results should now be stored in a truly unique artifact location
• Added explicit concurrency groups to release workflows
• Added explicit permissions to workflows (primarily to drop permissions as early as possible)

Closes #8511

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Project	Deployment	Actions	Updated (UTC)
lexical	Ready	Preview, Comment	May 14, 2026 1:33am
lexical-playground	Ready	Preview, Comment	May 14, 2026 1:33am