Adds round 3 MIGs for MIG migration

[nkinkade]

https://docs.google.com/document/d/1fX_ndIN2M0MiaguxONTTSXqR2C-JnsSs4PFReY45HuQ/edit#heading=h.b31qf7vzme12

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This change is 

[stephen-soltesz]

Reviewable status: complete! 1 of 1 approvals obtained (waiting on @nkinkade)

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sites/cmh02.jsonnet line 5 at r1 (raw file):

sitesDefault {
  name: 'cmh02',
  annotations+: {

some sites use probability 0.5, some use the default - are both correct?

[nkinkade]

Reviewable status: complete! 1 of 1 approvals obtained (waiting on @stephen-soltesz)

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sites/cmh02.jsonnet line 5 at r1 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

some sites use probability 0.5, some use the default - are both correct?

While you were on leave, I set all virtual sites to 50% probability that are colocated in metros that also have a physical site presence. All of these new MIGs are located in metros that also currently have at least one standalone VM. If the standalone VM had 50% probability, then I set the MIG to also have 50% probability in order to maintain this cost optimization, at least until the physical site(s) in those metros go away.