Prepare for 34-rc.2 (#644) #1206

Job	Run time
Build only sysroot - default	13m 49s
Build only sysroot - static	13m 12s
Build only sysroot - exceptions	11m 52s
Build arm64-linux	1h 50m 49s
Build x86_64-macos	55m 17s
Build arm64-macos	1h 23m 38s
Build x86_64-windows	2h 35m 21s
Build arm64-windows	4h 7m 15s
Build riscv64-linux	2h 1m 39s
Build x86_64-linux	2h 43m 16s
Test standalone toolchain	3m 52s
Finalize wasi-sdk artifacts	14m 10s
	16h 34m 10s

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