[Packaging] Add Ubuntu 21.10 Impish Indri support and drop Ubuntu 21.04 Hirsute Hippo support

[jiasli]

Description

• Close Install instructions don't work for Ubuntu 21.10 (No 21.10 debs are built) #20058

Per https://wiki.ubuntu.com/Releases:

• Ubuntu 21.04 Hirsute Hippo has reached End of Life. We should drop it.
• Ubuntu 21.10 Impish Indri is the latest release. We should support it. Customers running Impish can't install Azure CLI ( The repository 'https://packages.microsoft.com/repos/azure-cli bionic Release' does not have a Release file. MicrosoftDocs/azure-docs-cli#2256).

History Notes

[Packaging] Add Ubuntu 21.10 Impish Indri support
[Packaging] Drop Ubuntu 21.04 Hirsute Hippo support

[jiasli]

Building Python 3.6 on Impish fails

https://dev.azure.com/azure-sdk/public/_build/results?buildId=1334752&view=logs&j=3785ca6e-0e58-5722-c7f7-f718f26c5084&t=c716ad81-3cd2-56a0-7de7-4ff271e84af1

Segmentation fault (core dumped)
make: *** [Makefile:1102: install] Error 139

This is reported at https://bugs.python.org/issue45700

We need to bump the embedded Python to 3.8 first (#20869).

[jiasli]

Release CI task "Publish Debian Packages" has been updated accordingly: https://dev.azure.com/azure-sdk/internal/_releaseDefinition?definitionId=79&_a=definition-tasks&environmentId=153

[jiasli]

Unexpectedly, https://packages.microsoft.com/ doesn't support zstd-compressed deb packages generated by Ubuntu 21.10 Impish:

$ ar t azure-cli_2.33.1-1~impish_all.deb
debian-binary
control.tar.zst
data.tar.zst

Before Ubuntu 21.04, packages are zx-compressed.

$ ar t azure-cli_2.33.1-1~focal_all.deb
debian-binary
control.tar.xz
data.tar.xz

We will work with Microsoft Linux Repo team to make sure zstd compression is supported as soon as possible, before the release of the next LTS version of Ubuntu - 22.04 Jammy Jellyfish.