Tests

Fix TypeIs narrowing before isinstance #22544

Job	Run time
Test mypyc suite with 32-bit Python	9m 0s
Test suite with py310-ubuntu, mypyc-compiled	1m 39s
mypyc runtime tests with py313-macos	8m 3s
Test suite with py312-ubuntu	9m 4s
Test suite with py313-ubuntu, mypyc-compiled	1m 13s
Type check our own code (py310-ubuntu)	1m 1s
Test suite with py314t-ubuntu, mypyc-compiled	1m 27s
Test suite with py311-ubuntu	9m 5s
Parallel tests with py314-ubuntu, interpreted	9m 4s
mypyc runtime tests with py310-ubuntu	7m 34s
Test suite with py314-ubuntu, mypyc-compiled	1m 24s
Test suite with py314-windows-64	9m 0s
Formatting and code style with Black + ruff	1m 47s
Type check our own code (py310-windows-64)	1m 47s
Parallel tests with py314-windows-64, interpreted	8m 57s
Test suite with py315-ubuntu, mypyc-compiled	1m 49s
Parallel tests with py314-ubuntu, mypyc-compiled	1m 18s
	1h 23m 12s

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