[aarch64-port-dev ] RFR (XS): 8221529: [TESTBUG] Docker tests use old/deprecated image on AArch64

[Nick Gasson]

Hi Andrew,

 >
 > Nick will have to explain what it's supposed to do, and why.
 >

By default on all non-x86 Linux platforms the Docker tests are supposed 
to use the official Ubuntu "latest" (=18.04) image from Docker Hub. But 
for AArch64 the image used is "aarch64/ubuntu" which according to [1] is 
deprecated in favour of "arm64v8/ubuntu" and hasn't been updated since 
16.04:

"The aarch64 organization is deprecated in favor of the more-specific 
arm64v8 organization, as per 
https://github.com/docker-library/official-images#architectures-other-than-amd64. 
Please adjust your usages accordingly."

Practically, this causes problems if your JDK image is linked against a 
recent glibc: the Docker tests will fail with symbol resolution errors 
when these binaries are run in the Ubuntu 16.04 container.

[1] https://hub.docker.com/r/aarch64/ubuntu

Thanks,
Nick