Themes: Reset update notice when credentials modal is canceled

[ArkaPrabhaChowdhury]

Summary

• restore the theme details popup notice when the filesystem credentials modal is canceled
• add a QUnit regression test for the queued theme update cancel flow

Testing

• vendor/bin/phpcbf --standard=phpcs.xml.dist src/js/_enqueues/wp/updates.js tests/qunit/wp-admin/js/updates.js
• vendor/bin/phpcs --standard=phpcs.xml.dist src/js/_enqueues/wp/updates.js tests/qunit/wp-admin/js/updates.js
• npx tsc --build
• npx playwright test --config tests/qunit/playwright.config.js

Trac ticket: https://core.trac.wordpress.org/ticket/37669

[github-actions]

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[github-actions]

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