test(frontend): add ConflictingFileModalContentComponent unit tests

[Roshan3580]

Purpose of the PR

Closes #5467

This PR adds frontend unit tests for RegistrationRequestModalComponent.

Summary of Changes
Added registration-request-modal.component.spec.ts
Added a test to verify the component is created successfully
Added a test to verify modal data correctly seeds name and email
Added a test to verify null modal data falls back to empty strings
Added a test to verify getValues() trims whitespace from affiliation and reason
Design Proposal

N/A — this PR only adds unit tests for existing frontend behavior.

Technical Design Diagram/Description

N/A — no production logic or UI behavior was changed.

GIFs/Screenshots

N/A — test-only change.

Testing

Executed locally:

yarn test --include='**/registration-request-modal.component.spec.ts'
yarn lint

Both completed successfully.

[github-actions]

👋 Thanks for your first contribution to Texera, @Roshan3580!

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[Yicong-Huang]

@Roshan3580 please use our PR template. Please feel free to reopen once it is ready. Thanks!