service: add some unit test cases #2162

Job	Run time
contrib-build-master	5m 16s
nydus-build-master	1m 51s
cargo-deny	7m 49s
contrib-build	4m 6s
nydus-build	3m 13s
nydus-unit-test	8m 20s
nydus-unit-test-coverage	2m 35s
benchmark-nydus-no-prefetch	48s
benchmark-zran-no-prefetch	1m 24s
benchmark-nydus-all-prefetch	1m 0s
benchmark-nydus-filelist-prefetch	4m 21s
benchmark-oci	1m 19s
benchmark-zran-all-prefetch	1m 30s
nydus-integration-test	5m 33s
benchmark-zran-no-prefetch-master	1m 32s
benchmark-nydus-all-prefetch-master	1m 21s
benchmark-nydus-no-prefetch-master	31s
benchmark-nydus-filelist-prefetch-master	3m 24s
benchmark-zran-all-prefetch-master	1m 33s
benchmark-result	0s
benchmark-compare	9s
	57m 35s

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