Implementation plan: Ingestion server removal (#4026)

* Add initial plan

* Correct wording

Co-authored-by: sarayourfriend <[email protected]>

* Add clarifications and formatting fixes

* Adjust approach using ASG

* Add more detail about cost analysis and link to breakdown

* Fix link

* Add prior art

* Fix footnote

* Update link and trigger rule

* Accept aetherunbound approval

Co-authored-by: Madison Swain-Bowden <[email protected]>

* Lint approval

* Remove unnecessary step

* Clarify use of tags for ASGs, add -pool suffix

* Reference opportunity for future iteration

* Record sarayourfriend approval

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Co-authored-by: sarayourfriend <[email protected]>
Co-authored-by: Madison Swain-Bowden <[email protected]>