chore: Remove deprecated builds for CentOS 8 and Windows Server 2016

[tenthirtyam]

Summary of Pull Request

Remove the following deprecated in v21.08:

• Removes the deprecated CentOS 8 option; end-of-life as of December 31, 2021.
• Removes the deprecated Windows Server 2016 option; end-of-life as of January 11, 2022.

Type of Pull Request

• This is a bugfix.
• This is an enhancement or feature.
• This is a code style / formatting update.
• This is a documentation update.
• This is a refactoring update.
• This is something else.
  Please describe: chore

Test and Documentation Coverage

• Tests have been completed (for bugfixes / features).
• Documentation has been added / updated (for bugfixes / features).

Breaking Changes?

• Yes, there are breaking changes.
• No, there are no breaking changes.

[github-actions]

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