JIT

GH-136895: Update JIT builds to use LLVM 20 #4249

Job	Run time
Interpreter (Debug)	9m 54s
JIT without optimizations (Debug) (20)	10m 45s
Free-Threaded (Debug) (20)	15m 41s
i686-pc-windows-msvc/msvc (Release)	11m 53s
i686-pc-windows-msvc/msvc (Debug)	19m 49s
x86_64-apple-darwin/clang (Release)	21m 49s
aarch64-pc-windows-msvc/msvc (Release)	17m 31s
aarch64-pc-windows-msvc/msvc (Debug)	21m 39s
x86_64-pc-windows-msvc/msvc (Debug)	21m 1s
x86_64-pc-windows-msvc/msvc (Release)	14m 57s
aarch64-unknown-linux-gnu/gcc (Release)	5m 30s
x86_64-unknown-linux-gnu/gcc (Release)	6m 14s
aarch64-unknown-linux-gnu/gcc (Debug)	7m 13s
aarch64-apple-darwin/clang (Debug)	11m 47s
aarch64-apple-darwin/clang (Release)	12m 10s
x86_64-unknown-linux-gnu/gcc (Debug)	12m 26s
x86_64-apple-darwin/clang (Debug)	25m 30s
	4h 5m 49s

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