[MNT] Replace live server calls with mocks in test_run.py

[KanishqGandharv219]

Closes #1649 for test_run.py.

The issue was unclaimed for several days without an open PR, so I went ahead and implemented the mocks for the 6 tests marked with @pytest.mark.test_server().

Changes made:

• Removed @pytest.mark.test_server() and @pytest.mark.production_server() decorators
• Used unittest.mock.patch to intercept API calls (get_task, run_model_on_task, publish, etc.)
• Replaced actual API responses with mock.MagicMock objects populated with realistic attributes
• Maintained all meaningful logic and assertions (including saving/loading from the filesystem and structure comparisons)
• Tests now run completely offline and execution time dropped from ~30s to <1s.