az vm create gives warning about default size changing even when a size is specified

### Describe the bug

When creating a VM, you always receive a warning that the default size is going to change, even when you specified a value for `--size`. Since that change will only affect VMs created with the default size, that warning in this case is just noise.

### Related command

`az vm create [...] --size Standard_E2as_v5`

### Errors

`The default value of '--size' will be changed to 'Standard_D2s_v5' from 'Standard_DS1_v2' in a future release.`

### Issue script & Debug output

N/A

### Expected behavior

I expect the warning to only be shown when running `az vm create` without specifying a value for `--size`.

### Environment Summary

Cloud Shell bash

### Additional context

Although this happens to be from a `vm` command this time, it looks like this should actually be fixed in core: https://github.com/Azure/azure-cli/blob/bb2b31a832033e1b6e1343cc49b8ec023cd537fb/src/azure-cli-core/azure/cli/core/breaking_change.py