Unofficial Azure CLI deb packages are distributed by Linux repositories

Community packagers release **unofficial** Azure CLI deb packages on multiple Linux repositories. These packages are **not maintained by Microsoft**, outdated, and contain various bugs.

## Ubuntu

### 2.0.81 for Focal 20.04

Package: https://packages.ubuntu.com/source/focal/azure-cli
Issues: https://github.com/Azure/azure-cli/issues?q=is%3Aissue+2.0.81

### 2.18.0 for Hirsute 21.04

Package: https://packages.ubuntu.com/hirsute/python3-azure-cli
Issues: https://github.com/Azure/azure-cli/issues?q=is%3Aissue+2.18.0

## Debian

### 2.18.0 for Bullseye 11

Package: https://packages.debian.org/bullseye/azure-cli
Issues: https://github.com/Azure/azure-cli/issues?q=is%3Aissue+2.18.0

### 2.37.0 for sid (unstable)

Package: https://packages.debian.org/sid/azure-cli

## How unofficial Azure CLI is installed

### Ubuntu 20.04 Focal, Debian 11 Bullseye

The user doesn't follow the [Install the Azure CLI on Linux](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli-linux?pivots=apt) official document to add Microsoft Linux Repo (https://packages.microsoft.com/repos/azure-cli/) to `apt`. `apt install azure-cli` will install the above unofficial ones from Debian/Ubuntu repo.

### Debian sid

Even though the user added Microsoft Linux Repo (https://packages.microsoft.com/repos/azure-cli/) to `apt`, `apt update` fails because we don't release deb package for Debian sid:

```
# AZ_REPO=$(lsb_release -cs)
# echo "deb [arch=amd64] https://packages.microsoft.com/repos/azure-cli/ $AZ_REPO main" | tee /etc/apt/sources.list.d/azure-cli.list
# echo $AZ_REPO
sid
# apt update
Hit:1 http://deb.debian.org/debian sid InRelease
Ign:2 https://packages.microsoft.com/repos/azure-cli sid InRelease
Err:3 https://packages.microsoft.com/repos/azure-cli sid Release
404 Not Found [IP: 20.188.102.6 443]
Reading package lists... Done
E: The repository 'https://packages.microsoft.com/repos/azure-cli sid Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
```

`apt install azure-cli` will install the unofficial 2.37.0.