fix bash API-download script downloading ARM packages on non-ARM hosts

[joekohlsdorf]

On Ubuntu 18/20 x86_64 the script tried to install the ARM64 package which was the first in the list with the "os_version": "18/20 - arm64".

This change makes the installer compatible with both ARM and non-ARM packages.

[joekohlsdorf]

By the way, the installers API should a) return the architecture in a separate field b) have a filter for the architecture

The current way of doing this is a terrible hack.

[redhatrises]

@joekohlsdorf would you mind adding this to the https://github.com/CrowdStrike/falcon-scripts/blob/main/bash/install/falcon-linux-install.sh script which has a lot more functionality? We'd like to deprecate this script in favor of the new one.

[joekohlsdorf]

I won't add it to the other script because I'm not using it and I don't have any experience using it. But feel free to incorporate the ideas/code of the PRs I proposed into the new script, it looks like it has the same issues.