Test

fix hls & dash segments cleanup. #3629

Job	Run time
cygwin64-cache	1m 48s
multiple-arch-aarch64	22m 53s
utest-regression-blackbox-test	9m 42s
multiple-arch-armv7	21m 56s
fast	1s
cygwin64	15m 23s
build-cross-aarch64	5m 1s
build-cross-arm	5m 17s
build-centos7	4m 57s
build-ubuntu16	3m 9s
build-ubuntu18	3m 6s
build-ubuntu20	3m 28s
coverage	3m 39s
multiple-arch-amd64	2m 20s
test-done	1s
	1h 42m 41s

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