Build: Only generate asset file once and keep version consistent

[youknowriad]

Related WordPress/wordpress-develop#10638

Problem

Both minified and non-minified builds were generating the same .asset.php file concurrently, causing a race condition. The hash would alternate between two values depending on which build finished last:

• Minified build: hash of index.min.js + index.min.js.map
• Non-minified build: hash of index.js + index.js.map

This made builds non-deterministic, causing unnecessary git diffs on every rebuild.

Solution

• Added generateAssetFile parameter to wordpressExternalsPlugin() (defaults to true)
• Only the minified build now generates the .asset.php file
• Non-minified build skips asset file generation entirely

This ensures each .asset.php file is written exactly once with a consistent hash.

Testing

Verified multiple consecutive builds produce identical .asset.php files with stable hashes.

[github-actions]

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[github-actions]

Flaky tests detected in 10cb4cc.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/20276620816
📝 Reported issues:

• [Flaky Test] should allow user to add and remove multiple local font files #62862 in /test/e2e/specs/site-editor/font-library.spec.js