[Autoscaler][Azure] check if 'update' is available in

[ijrsvt]

Why are these changes needed?

• Newer versions of the Azure client do not seem to have VirtualMachineOperations::update, and instead have VirtualMachineOperations::begin_update.

Related issue number

Closes #14778

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[ijrsvt]

@gramhagen Where can I find the lifecycle of update vs begin_update? I tried looking at some online docs and even looking at pervious versions, I saw now reference to update. That being said, I looked at the local python source code for the package, and saw update.

[gramhagen]

I believe the change happens >= 17

Check release notes for 17.0.0b1 https://pypi.org/project/azure-mgmt-compute/

[DmitriGekhtman]

Thanks, lgtm!