test(generator): add coverage for hide_title parameter in generateSVG

[Subhooo5]

Description

Fixes #722

• Added generator-level test coverage for the hide_title parameter, verifying that the username title is correctly omitted when enabled.
• Added a complementary assertion ensuring the uppercase username title still renders normally when hide_title is disabled.

Pillar

• 🛠️ Other (Bug fix, refactoring, docs)

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak?user=YOUR_USERNAME).
• I have run npm run format and npm run lint locally and resolved all errors.
• My commits follow the Conventional Commits format.
• I have starred the repo.
• I have made sure that i have only one commit to merge in this PR.

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[Subhooo5]

Hey @JhaSourav07 Successfully added the required test. All existing tests pass locally. Feel free to review, add necessary labels and merge it. 🫂🚀