Enable AKS BYO nodepool test spec

[mboersma]

/kind cleanup

What needs cleanup:

The AKSBYONodeSpec was temporarily disabled in #5151, but should be restored when CAPZ reference image publishing catches up with AKS.

Describe the solution you'd like [Description of how you would like the cleanup to be done.]

Files to change: 1

• [ ] test/e2e/azure_test.go
  • 856-866

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

[nojnhuh]

This will involve reverting #5151 and its backports to release branches, so these three PRs in total:

• 5151

• 5152

• 5154