Switch our CentOS 8 naming to use AlmaLinux on Install Page

Why is this change being made?

CentOS 8 is reaching it's end-of-life on December 31st - https://www.centos.org/centos-linux-eol/ and we have validated AlmaLinux as the distro we will be supporting instead of CentOS 8. (CentOS 7 remains supported as it has a later end-of-life).

I did consider switching to using RHEL8 as our tile here, but RHEL doesn't have a product/project logo without text. And even the company logo is usually with text and they ask you to reach out to them if you plan to use it without text. (And we are more interested in a distro logo here, rather than a company logo).

The logo I used here is the SVG from AlmaLinux's Brand Guidelines with a single pass through svgo to remove the extra metadata left by the svg editor.

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