W-16266355 Remove unsupported Linux distros (1.8)

[chris-campbell9]

Writer's Quality Checklist

Before merging your PR, did you:

• [ ] Run spell checker
• [ ] Run link checker to check for broken xrefs
• [ ] Check for orphan files
• [ ] Perform a local build and do a final visual check of your content, including checking for:
  • Broken images
  • Dead links
  • Correct rendering of partials if they are used in your content
  • Formatting issues, such as:
  • Misnumbered ordered lists (steps) or incorrectly nested unordered lists
  • Messed up tables
  • Proper indentation
  • Correct header levels
• [ ] Receive final review and signoff from:
  • Technical SME
  • Product Manager
  • Editor or peer reviewer
  • Reporter, if this content is in response to a reported issue (internal or external feedback)
• [ ] If applicable, verify that the software actually got released