Move all toolchain installation in TOOLCHAIN directory. #2165

Job	Run time
Macos (native_dyn)	1s
Macos (native_static)	1s
Macos (native_mixed)	1s
Flatpak	17m 42s
Macos (iOS_arm64)	1s
Macos (iOS_x86_64)	1s
Linux (native_static, focal)	10m 14s
Macos (iOS_Mac_ABI)	1s
Linux (native_dyn, focal)	9m 32s
Macos (macOS_arm64_static)	1s
Linux (native_mixed, focal)	5m 29s
Macos (macOS_arm64_mixed)	1s
Linux (wasm, focal)	16m 54s
Macos (macOS_x86_64)	1s
Linux (armv6_static, focal)	4m 4s
Linux (armv6_dyn, focal)	2m 52s
Linux (armv6_mixed, focal)	3m 26s
Linux (armv8_static, focal)	4m 14s
Linux (armv8_dyn, focal)	2m 50s
Linux (armv8_mixed, focal)	3m 16s
Linux (aarch64_static, focal)	17m 18s
Linux (aarch64_dyn, focal)	12m 25s
Linux (aarch64_mixed, focal)	13m 41s
Linux (aarch64_musl_static, focal)	3m 26s
Linux (aarch64_musl_dyn, focal)	4m 14s
Linux (aarch64_musl_mixed, focal)	3m 9s
Linux (x86-64_musl_static, focal)	2m 40s
Linux (x86-64_musl_dyn, focal)	3m 4s
Linux (x86-64_musl_mixed, focal)	3m 42s
Linux (i586_static, focal)	3m 9s
Linux (i586_dyn, focal)	2m 22s
Linux (android_arm, focal)	11m 19s
Linux (android_arm64, focal)	11m 39s
Linux (android_x86, focal)	13m 8s
Linux (android_x86_64, focal)	13m 8s
Linux (native_mixed, bionic)	1m 48s
Linux (aarch64_mixed, bionic)	12m 39s
Linux (win32_static, f35)	5m 22s
Linux (win32_dyn, f35)	3m 41s
	3h 42m 36s

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