[FEATURE REQUEST] Upgrade Kubernetes to 1.20.x

[atsikham]

Is your feature request related to a problem? Please describe.
Upgrade K8s to 1.20.x to be able to perform future upgrades.

Describe the solution you'd like
Upgrade K8s to 1.20.x with dependencies: CNI plugins, dashboard, etc. Check release notes for that, deprecated things should be removed/updated.

Additional information
The Kubernetes project maintains release branches for the most recent three minor releases (1.22, 1.21, 1.20). Kubernetes 1.19 and newer receive approximately 1 year of patch support. Kubernetes 1.18 and older received approximately 9 months of patch support.

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DoD checklist

• Changelog updated
• COMPONENTS.md updated / doesn't need to be updated
• Schema updated / doesn't need to be updated
• Feature has automated tests
• Automated tests passed (QA pipelines)
  • apply
  • upgrade
• Idempotency tested
• Documentation added / updated / doesn't need to be updated
• All conversations in PR resolved
• Solution meets requirements and is done according to design doc
• Usage compliant with license
• Backport tasks created / doesn't need to be backported

[przemyslavic]

✔️ upgrade from v1.0 (1 master + 2 nodes)
✔️ upgrade from v1.1 HA (3 masters + 2 nodes)
✔️ upgrade from v1.1 aarch64 (1 master + 2 nodes)
✔️ upgrade from v1.2 single machine installation (1 master)
✔️ apply aarch64 (1 master + 2 nodes) + reapply
✔️ apply x86_64 (1 master + 2 nodes) + reapply
✔️ apply single machine installation (1 master) + reapply
✔️ apply HA (3 masters + 2 nodes) + reapply
✔️ apply promote to HA (1 -> 3 masters + 2 nodes)