Update deb_install.sh to use /etc/apt/keyrings

## Issue

The apt-key command is [deprecated](https://itsfoss.com/apt-key-deprecated/) with Ubuntu 22.04 (except for deletes).

The `/usr/share/keyrings` directory is the recommended location for package signing keys now, rather than `/etc/apt/keyrings`.

The [deb_install.sh script](https://github.com/Azure/azure-cli/blob/dev/scripts/release/debian/deb_install.sh) used by [option 1](https://learn.microsoft.com/cli/azure/install-azure-cli-linux?pivots=apt#option-1-install-with-one-command) would benefit from changing to these newer standards. The [manual commands](https://learn.microsoft.com/cli/azure/install-azure-cli-linux?pivots=apt) are slightly better as they include the `signed-by` location, but again, should that location now be `/usr/share/keyring`?