Move build kit env vars back to build args #73

Job	Run time
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 13)	1m 53s
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 12)	1m 39s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 14)	2m 14s
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 14)	1m 52s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 20)	1m 26s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 12)	2m 22s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 13)	2m 46s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 16)	1m 38s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 17)	1m 35s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 19)	1m 38s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 16)	2m 21s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 18)	1m 46s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 20)	1m 54s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 19)	2m 19s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 17)	2m 32s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 18)	1m 26s
merge	-1s
	31m 20s

Provide feedback