refactor: remove container from list of run image types (#2178)

# What does this PR do?
[Provide a short summary of what this PR does and why. Link to relevant
issues if applicable.]
Removes the ability to run llama stack container images through the
llama stack CLI
Closes #2110
## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]
Run:
```
llama stack run /path/to/run.yaml --image-type container
```
Expected outcome:
```
llama stack run: error: argument --image-type: invalid choice: 'container' (choose from 'conda', 'venv')
```

[//]: # (## Documentation)

llama_stack/cli/stack/run.py

@@ -59,7 +59,7 @@ class StackRun(Subcommand):
             "--image-type",
             type=str,
             help="Image Type used during the build. This can be either conda or container or venv.",
-            choices=[e.value for e in ImageType],
+            choices=[e.value for e in ImageType if e.value != ImageType.CONTAINER.value],
         )
         self.parser.add_argument(
             "--enable-ui",