ST: Use coroutine to execute valgrind check. #1622

Job	Run time
cygwin64-cache	2m 0s
multiple-arch-armv7	20m 26s
multiple-arch-aarch64	22m 0s
utest-regression-blackbox-test	9m 33s
cygwin64	14m 15s
fast	1s
build-ubuntu20	3m 34s
build-ubuntu16	3m 3s
build-centos7	4m 56s
build-cross-aarch64	5m 29s
build-cross-arm	5m 17s
build-ubuntu18	3m 13s
coverage	3m 31s
multiple-arch-amd64	2m 22s
test-done	1s
	1h 39m 41s

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