Tests

Preserve some lost narrowing, cleanup (#20674) #20478

Job	Run time
Test mypyc suite with 32-bit Python	9m 16s
Test suite with py310-ubuntu, mypyc-compiled	15m 29s
Test suite with py312-ubuntu	8m 48s
Test suite with py314t-ubuntu, mypyc-compiled	16m 12s
mypyc runtime tests with py310-ubuntu	5m 30s
Parallel tests with py314-ubuntu, interpreted	25m 57s
Parallel tests with py314-ubuntu, mypyc-compiled	31m 18s
Test suite with py311-ubuntu	8m 42s
Test suite with py314-windows-64	27m 9s
mypyc runtime tests with py313-macos	5m 28s
Test suite with py313-ubuntu, mypyc-compiled	14m 16s
Type check our own code (py310-windows-64)	2m 19s
Formatting and code style with Black + ruff	1m 55s
Type check our own code (py310-ubuntu)	1m 40s
Test suite with py314-ubuntu, mypyc-compiled	14m 3s
	3h 8m 2s

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