Refactor: src/screens/BlockUser from Jest to Vitest

[VanshikaSabharwal]

Is your feature request related to a problem? Please describe.
This file is currently tested using Jest. As part of our migration to Vitest, we need to refactor this file's test cases to align with Vitest's syntax and features.

Acceptance Criteria

1. Replace Jest-specific functions and mocks with Vitest equivalents
2. Ensure all tests in src/screens/BlockUser pass after migration using npm run test:vitest
3. Maintain the test coverage for the file as 100% after migration
4. Upload a video or photo for this specific file coverage is 100% in the PR description

Additional context

• Refer to the merged PR for the base Vitest configuration:
  https://github.com/PalisadoesFoundation/talawa-admin/pull/2457/files#diff-9a5a35cf8d7f02b2bba90905714b762560579c4789e9eb4cebb4607980aa3d93
• Vitest documentation:
  https://vitest.dev/

Potential internship candidates

Please read this if you are planning to apply for a Palisadoes Foundation internship

• Student Internship Programs talawa#359

[amitb0ra]

hey @varshith257, can you assign this to me?

[github-actions]

This issue did not get any activity in the past 10 days and will be closed in 180 days if no update occurs. Please check if the develop branch has fixed it and report again or close the issue.

[amaan-aly246]

@varshith257 Assign this issue to me if possible.
Thanks