Tests

Fix some compiler warnings about unused vars #19632

Job	Run time
Test mypyc suite with 32-bit Python	9m 7s
Test suite with py310-ubuntu, mypyc-compiled	13m 37s
Test suite with py312-ubuntu	9m 57s
Test suite with py311-ubuntu	8m 48s
Test suite with py314-ubuntu, mypyc-compiled	13m 4s
Test suite with py313-ubuntu, mypyc-compiled	14m 20s
Test suite with py314-windows-64	26m 23s
Type check our own code (py310-ubuntu)	1m 29s
mypyc runtime tests with py313-macos	4m 35s
Type check our own code (py310-windows-64)	2m 21s
mypyc runtime tests with py310-ubuntu	5m 8s
Parallel tests with py314-ubuntu, mypyc-compiled	25m 59s
Formatting and code style with Black + ruff	1m 59s
Parallel tests with py314-ubuntu, interpreted	22m 15s
	2h 39m 2s

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