tests/unit/test_main.py: Restore DB_CONF after test case execution

[bernhardkaindl]

tests/unit/test_main.py: Restore DB_CONF (xapi db config) after test case execution

Fix the fixture which provides a patched bugtool for normal execution as an unprivileged user for tests:

• To avoid leaking the patched DB_CONF string to other test cases, restore it after the test case.

Summary:

• Converts the patched_bugtool into a yielding generator fixture.
  It:
  1. Saves the original DB_CONF,
  2. Patches the loaded bugtool module
  3. Yields the test parameters to the test execution, and
  4. After the test is done, it restores the DB_CONF string to its original value.

[Copilot]

Pull Request Overview

This PR fixes a test isolation issue in the patched_bugtool fixture by ensuring the DB_CONF attribute is properly restored after each test case execution.

• Converts the fixture from a simple return to a generator with yield to enable proper cleanup
• Saves and restores the original DB_CONF value to prevent test interference
• Adds documentation clarifying the function-scoped nature of the fixture

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[Copilot]

Pull Request Overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

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