UnixPB: Fix Problematic Centos6 Downloads

[steelhead31]

Fixes #3839

Downloads for Git Source and Nvidia Cuda toolkit are failing on CentOS6 due to the certificate errors, and the lack of support of SNI enabled validation, due to the age of the O/S.

This PR adds an alternative, but still secure download mechanism for CentOS6 only, to allow the playbook to be backwards compatible.

Checklist

• commit message has one of the standard prefixes
• playbook changes run through VPC or QPC (if you have access)

VPC In Progress : https://ci.adoptium.net/job/VagrantPlaybookCheck/2061/

[sxa]

A couple of minor points and one thought (which I wouldn't address in this PR regardless): Is it worth just using wget/curl everywhere instead of having this duplicated?

[steelhead31]

A couple of minor points and one thought (which I wouldn't address in this PR regardless): Is it worth just using wget/curl everywhere instead of having this duplicated?

Ansible doesnt particularly like commands being delegated to the shell, it prefers the get_url function... but definitely something to consider.

[sxa]

As long as the ansible_distribution in ["CentOS", "RedHat"] syntax works everywhere we run ansible then I'm ok with this (Not sure we're written the expressions like that anywhere else)

[steelhead31]

As long as the ansible_distribution in ["CentOS", "RedHat"] syntax works everywhere we run ansible then I'm ok with this (Not sure we're written the expressions like that anywhere else)

I've just encountered an issue with this syntax, despite it working ok locally, I've amended it to be more uniform.