proxy dockerfile #3603

Job	Run time
cygwin64-cache	1m 45s
multiple-arch-aarch64	22m 58s
utest-regression-blackbox-test	9m 28s
multiple-arch-armv7	22m 33s
fast	1s
cygwin64	14m 36s
build-ubuntu16	3m 2s
build-centos7	5m 1s
coverage	3m 37s
multiple-arch-amd64	2m 15s
build-cross-aarch64	5m 0s
build-cross-arm	5m 20s
build-ubuntu20	3m 31s
build-ubuntu18	3m 10s
test-done	1s
	1h 42m 18s

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