[3.14] gh-145779: Improve classmethod/staticmethod scaling in free-th… #2430

Job	Run time
x86_64-unknown-linux-gnu/gcc	8m 56s
aarch64-unknown-linux-gnu/gcc	6m 44s
aarch64-apple-darwin/clang	8m 48s
x86_64-apple-darwin/clang	17m 4s
x86_64-unknown-linux-gnu/gcc-free-threading	8m 29s
x86_64-pc-windows-msvc/msvc	13m 29s
	1h 3m 30s

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