docs: clarify CLI option help and parallel errors

[Hashim1999164]

Overview

Clarifies Mocha CLI help text and shortens --parallel conflict errors per #6165.

Checklist

• Addresses an existing open issue: fixes 📝 Docs: Update options output (help, errors) #6165
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Summary

• Clarify --pass-on-failing-test-suite and --global help text wording
• Shorten --parallel conflict errors with --file / --sort
• Keep the CLI docs help excerpt in sync

Test plan

• Confirm mocha --help shows the updated descriptions
• Confirm --parallel --file and --parallel --sort still error with the shorter messages
• Existing parallel integration tests still match /mutually exclusive with --file|sort/

[linux-foundation-easycla]

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[github-actions]

👋 Hi @Hashim1999164, thanks for the pull request! A scan flagged a concern with it. Could you please take a look?

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• That issue was marked as status: accepting prs

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