Tests

Fix various test flakiness on Windows (#21220) #21743

Job	Run time
Test mypyc suite with 32-bit Python	10m 1s
Test suite with py311-ubuntu	9m 8s
Parallel tests with py314-windows-64, interpreted	8m 29s
Test suite with py314t-ubuntu, mypyc-compiled	17m 44s
Test suite with py310-ubuntu, mypyc-compiled	15m 35s
Test suite with py314-windows-64	29m 13s
Test suite with py312-ubuntu	9m 15s
Type check our own code (py310-ubuntu)	1m 11s
Parallel tests with py314-ubuntu, interpreted	27m 5s
Test suite with py314-ubuntu, mypyc-compiled	15m 37s
mypyc runtime tests with py313-macos	7m 21s
Type check our own code (py310-windows-64)	1m 47s
Parallel tests with py314-ubuntu, mypyc-compiled	27m 7s
Formatting and code style with Black + ruff	1m 52s
Test suite with py313-ubuntu, mypyc-compiled	15m 5s
mypyc runtime tests with py310-ubuntu	6m 29s
	3h 22m 59s

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