Add vm migration Grafana dashboard (backport #953)

[mergify]

Problem:

Solution:

Related Issue:
related to harvester/harvester#4352
upgrade path pr: harvester/harvester#7551

Test plan:

• Prepare a 3 node harvester cluster
• Enable rancher-monitoring addon
• Migration normally goes fast, so please restrict migration bandwidth to 2Mi first

  kubectl patch kubevirt kubevirt -n harvester-system --type merge -p '{"spec":{"configuration":{"migrations":{"bandwidthPerMigration":"2Mi"}}}}'
  

• Create 2 vm, test, test2 (2 cpu, 2GB ram for each)
• Migrate vm test to another node.
• On VM test2, install stress and run a memory stress test to verify that the dirty memory rate is nonzero. Then, migrate VM test2 to another node.

sudo apt install stress
stress --vm 2 --vm-bytes 100M --timeout 86400s

• Go to grafana “Harvester VM Migration Details” dashboard
  • click Add-ons > rancher-monitoring > Grafana > click Grafana icon > Dashboards > Harvester VM Migration Details

Here is the sample screenshot:

vm test migration

vm test2 migration

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This is an automatic backport of pull request #953 done by [Mergify](https://mergify.com).

[w13915984028]

LGTM, thanks.

[ihcsim]

Per slack chat, rebasing this on top of #957 should fix the CI error.