test: fill coverage gaps in `languages/python`

[KRRT7]

Parent: #2079

Phase 3 — languages/python to 100%

Module	Stmts	Current coverage
languages/python	4,587	81%

Key files needing attention:

• python/optimizer.py (30 stmts, 30%)
• python/function_optimizer.py (133 stmts, 38%)
• python/test_runner.py (40 stmts, 42%)
• python/support.py (574 stmts, 60%)
• python/parse_xml.py (121 stmts, 64%)
• python/reference_graph.py (294 stmts, 73%)
• python/normalizer.py (103 stmts, 81%)
• python/context/code_context_extractor.py (1,113 stmts, 86%)
• python/static_analysis/code_extractor.py (677 stmts, 85%)

Already well-covered files (>90%) just need gap-filling:

• python/instrument_codeflash_capture.py (99%)
• python/static_analysis/coverage_utils.py (98%)
• python/static_analysis/edit_generated_tests.py (95%)
• python/context/unused_definition_remover.py (94%)

Target

100% coverage for languages/python (~4,587 statements).