[ONPREM-2668] Update server air-gapped images lists for 4.8.5 and 4.7.12

[christian-stephen]

Description

What did you change?

Update the server air-gapped installation instructions to reference the most up-to-date images as of patch versions 4.8.5 and 4.7.12 (the latest).

Reasons

Why did you make these changes?

https://circleci.atlassian.net/browse/ONPREM-2668

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