[EPIC] GOV.UK Running on Graviton

[dj-maisy]

What?

This is an "Epic" to make the entirety of GOV.UK run on Graviton and ARM.

Tasks

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1. Start running most workloads on ARM in Staging govuk-helm-charts#2849
   ARM enhancement k8s +3
   
2. Migrate DGU to Graviton/ARM govuk-helm-charts#2165
   2 of 2
   ARM +1
   
3. Track Performance Metrics for GOV.UK on Graviton #1402
   0 of 1
   ARM +1
   
4. Enable ARM Workers pool on Staging #1511
   +0
5. Enable ARM builds for "sidecar" images. #1290
   +0
6. Switch the ARM Worker ASG default amounts. #1285
   +0
7. Add Taint restriction to ARM Nodes #1232
   +0
8. We have run out of capacity on Integration for ARM #1284
   +0
9. Fix the arch taint for the arm node pool. #1262
   +0
10. Add optional ARM Node Group Config #1203
    +0
11. Shared multiarch workflow will now use Github ARM #1251
    +0