fix: resolve TypeError in TLS verification unit tests-#1414

[Rakshak05]

Closes #1414

Description

This PR resolves the TypeError: 'coroutine' object does not support the asynchronous context manager protocol failure in the TLS verification unit tests.

Key Changes:

• Crawler Tests: Mocked the client.stream async context manager and the aiter_bytes generator in TestCrawlerVerifySsl to match the new client.stream implementation in crawler.py.
• API Scanner Tests: Mocked the crawl_target function inside the TestAPIScannerVerifySsl tests to isolate the API scanner testing flow and avoid running the actual client stream method.

Related Issues

Closes #1736 (TLS verification regression tests)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

Ran the backend unit tests locally using:

pytest testing/backend/unit/test_tls_verification.py

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.

[utksh1]

Clean test fix. Updates TLS verification test mocks to match the actual crawler.py implementation:

• Mock client.stream async context manager instead of client.get
• Add mock_aiter_bytes generator for streaming response
• Mock crawl_target in API scanner tests for isolation

All CI passing. Merging.