test(e2e): standardize file content assertions using helper functions

[chenjiahan]

Summary

Standardize file content assertions using helper functions for better error messages and consistency.

Related Links

#6248

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull Request Overview

This PR standardizes file content assertions in e2e tests by replacing manual file finding patterns with helper functions findFile and getFileContent for better error messages and consistency.

• Introduces helper functions for consistent file finding and content retrieval
• Updates HASH_PATTERN regex to match 8+ character hashes instead of 6+
• Improves error messages with colored output for better debugging

Reviewed Changes

Copilot reviewed 91 out of 91 changed files in this pull request and generated 3 comments.

File	Description
e2e/helper/utils.ts	Updates HASH_PATTERN regex and improves error message formatting with colors
e2e/cases/*/index.test.ts	Standardizes file content assertions by replacing manual Object.keys(files).find() patterns with findFile and getFileContent helper functions
e2e/cases/polyfill/helper.ts	Refactors polyfill content retrieval to use helper functions with proper function matchers

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