CI: Enable parallel build for riscv-tests.sh #2745

Job	Run time
detect-code-related-file-changes	5s
detect-code-related-file-changes	5s
detect-code-related-file-changes	5s
host-arm64	12m 31s
host-arm64	12m 31s
host-arm64	12m 31s
static-analysis	2m 59s
static-analysis	2m 59s
static-analysis	2m 59s
compliance-test	8m 17s
compliance-test	8m 17s
compliance-test	8m 17s
coding-style	8s
coding-style	8s
coding-style	8s
docker-hub-build-and-publish	13s
docker-hub-build-and-publish	13s
docker-hub-build-and-publish	13s
host-x64 (gcc)	2m 2s
host-x64 (gcc)	3m 23s
host-x64 (gcc)	3m 58s
host-x64 (clang)	3m 23s
host-x64 (clang)	3m 21s
host-x64 (clang)	4m 25s
	1h 33m 11s

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