proxy dockerfile #3633

Job	Run time
multiple-arch-aarch64	23m 18s
cygwin64-cache	1m 47s
multiple-arch-armv7	22m 6s
utest-regression-blackbox-test	9m 29s
cygwin64	14m 14s
fast	1s
build-cross-aarch64	5m 34s
build-centos7	4m 57s
build-cross-arm	5m 20s
build-ubuntu16	3m 10s
build-ubuntu18	3m 10s
coverage	3m 37s
build-ubuntu20	3m 32s
multiple-arch-amd64	2m 16s
test-done	1s
	1h 42m 32s

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