text: Title: Azure image-id from marketplace with :latest fails
  Body: <!-- Describe the bug report / feature request here -->
  Referencing a "latest" VM image from the Azure marketplace like `Canonical:ubuntu-24_04-lts:server:latest` does not work:
  ```
  Traceback (most recent call last):
    File "/home/cooperc/.local/bin/sky", line 8, in <module>
      sys.exit(cli())
               ^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/click/core.py", line 1157, in __call__
      return self.main(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/click/core.py", line 1078, in main
      rv = self.invoke(ctx)
           ^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/utils/common_utils.py", line 366, in _record
      return f(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/cli.py", line 838, in invoke
      return super().invoke(ctx)
             ^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/click/core.py", line 1688, in invoke
      return _process_result(sub_ctx.command.invoke(sub_ctx))
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/click/core.py", line 1434, in invoke
      return ctx.invoke(self.callback, **ctx.params)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/click/core.py", line 783, in invoke
      return __callback(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/utils/common_utils.py", line 386, in _record
      return f(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/cli.py", line 1118, in launch
      task_or_dag = _make_task_or_dag_from_entrypoint_with_overrides(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/cli.py", line 818, in _make_task_or_dag_from_entrypoint_with_overrides
      task.set_resources_override(override_params)
    File "/home/cooperc/a/skypilot/sky/task.py", line 664, in set_resources_override
      new_resources = res.copy(**override_params)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/resources.py", line 1261, in copy
      resources = Resources(
                  ^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/resources.py", line 249, in __init__
      self._try_validate_image_id()
    File "/home/cooperc/a/skypilot/sky/resources.py", line 929, in _try_validate_image_id
      image_size = self.cloud.get_image_size(image_id, region)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/skypilot/sky/clouds/azure.py", line 202, in get_image_size
      image = compute_client.virtual_machine_images.get(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/azure/core/tracing/decorator.py", line 105, in wrapper_use_tracer
      return func(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^
    File "/home/cooperc/a/sky-venv/lib/python3.11/site-packages/azure/mgmt/compute/v2024_07_01/operations/_operations.py", line 18308, in get
      raise HttpResponseError(response=response, error_format=ARMErrorFormat)
  azure.core.exceptions.HttpResponseError: (InvalidParameter) The value of parameter version is invalid.
  Code: InvalidParameter
  Message: The value of parameter version is invalid.
  Target: version
  ```
  
  It seems like `virtual_machine_images.get` cannot cope with the `latest` version for some reason. Using a specific version (e.g. `Canonical:ubuntu-24_04-lts:server:24.04.202411030`) works.
  
  <!-- If relevant, fill in versioning info to help us troubleshoot -->
  _Version & Commit info:_
  * `sky -v`: skypilot, version 1.0.0-dev0
  * `sky -c`: skypilot, commit 6c9acac5df3d6fc13a6a7e19deb35715163beddd-dirty
  