Scripts: Deprecated or remove Puppeteer as e2e test handler

[Mamaduka]

Extracted from #59311.

Now that core is fully migrated to Playwright and is the recommended library for running e2e tests, let's consider gracefully deprecating or fully removing Puppeteer from the scripts package.

[youknowriad]

I think it should be ok to remove and mark the change as breaking change. People will have to update the package manually anyway.

That said, we need to answer the fact that some people would want to continue using puppeteer while updating scripts package. In that case, I think it's a documentation thing. It should be possible to install puppeteer and run it directly for them without needing us to provide it in wp-scripts.

[Mamaduka]

We could update the test-e2e.js script and print some helpful upgrade guide - install puppeteer, etc.

This seems like the right place to do it.

gutenberg/packages/scripts/scripts/test-e2e.js

Lines 31 to 37 in 6accdd3

	const result = spawn( 'node', [ require.resolve( 'puppeteer-core/install' ) ], {
	stdio: 'inherit',
	} );
	if ( result.status > 0 ) {
	process.exit( result.status );
	}

[youknowriad]

Shouldn't we update test-e2e to use playwright instead? and if we detect puppeteer tests somehow render the upgrade guide?

[Mamaduka]

That would be nice, but we need to figure out how to detect puppeteer tests.

I guess if we're going for a breaking change, we could:

• Fully move to Playwright in wp-scripts. Making test-e2e and test-playwright aliases.
• Write up migration guide for the puppeteer and legacy test runner.
• Mention the migration guide in the changelog.