chore!: remove --image-type and --image-name from llama stack run

# What does this PR do?


## Test Plan

llama_stack/cli/stack/_build.py

@@ -444,12 +444,22 @@ def _run_stack_build_command_from_build_config(
 
         cprint("Build Successful!", color="green", file=sys.stderr)
         cprint(f"You can find the newly-built distribution here: {run_config_file}", color="blue", file=sys.stderr)
-        cprint(
-            "You can run the new Llama Stack distro via: "
-            + colored(f"llama stack run {run_config_file} --image-type {build_config.image_type}", "blue"),
-            color="green",
-            file=sys.stderr,
-        )
+        if build_config.image_type == LlamaStackImageType.VENV:
+            cprint(
+                "You can run the new Llama Stack distro (after activating "
+                + colored(image_name, "cyan")
+                + ") via: "
+                + colored(f"llama stack run {run_config_file}", "blue"),
+                color="green",
+                file=sys.stderr,
+            )
+        elif build_config.image_type == LlamaStackImageType.CONTAINER:
+            cprint(
+                "You can run the container with: "
+                + colored(f"docker run -p 8321:8321 -v ~/.llama:/root/.llama localhost/{image_name} --port 8321", "blue"),
+                color="green",
+                file=sys.stderr,
+            )
         return distro_path
     else:
         return _generate_run_config(build_config, build_dir, image_name)

llama_stack/cli/stack/run.py

@@ -55,12 +55,12 @@ class StackRun(Subcommand):
             "--image-name",
             type=str,
             default=None,
-            help="Name of the image to run. Defaults to the current environment",
+            help="[DEPRECATED] This flag is no longer supported. Please activate your virtual environment before running.",
         )
         self.parser.add_argument(
             "--image-type",
             type=str,
-            help="Image Type used during the build. This can be only venv.",
+            help="[DEPRECATED] This flag is no longer supported. Please activate your virtual environment before running.",
             choices=[e.value for e in ImageType if e.value != ImageType.CONTAINER.value],
         )
         self.parser.add_argument(
@@ -106,11 +106,18 @@ class StackRun(Subcommand):
         import yaml
 
         from llama_stack.core.configure import parse_and_maybe_upgrade_config
-        from llama_stack.core.utils.exec import formulate_run_args, run_command
+
+        if args.image_type or args.image_name:
+            self.parser.error(
+                "The --image-type and --image-name flags are no longer supported.\n\n"
+                "Please activate your virtual environment manually before running `llama stack run`.\n\n"
+                "For example:\n"
+                "  source /path/to/venv/bin/activate\n"
+                "  llama stack run <config>\n"
+            )
 
         if args.enable_ui:
             self._start_ui_development_server(args.port)
-        image_type, image_name = args.image_type, args.image_name
 
         if args.config:
             try:
@@ -122,10 +129,6 @@ class StackRun(Subcommand):
         else:
             config_file = None
 
-        # Check if config is required based on image type
-        if image_type == ImageType.VENV.value and not config_file:
-            self.parser.error("Config file is required for venv environment")
-
         if config_file:
             logger.info(f"Using run configuration: {config_file}")
 
@@ -140,23 +143,8 @@ class StackRun(Subcommand):
                     os.makedirs(str(config.external_providers_dir), exist_ok=True)
             except AttributeError as e:
                 self.parser.error(f"failed to parse config file '{config_file}':\n {e}")
-        else:
-            config = None
 
-        # If neither image type nor image name is provided, assume the server should be run directly
-        # using the current environment packages.
-        if not image_type and not image_name:
-            logger.info("No image type or image name provided. Assuming environment packages.")
-            self._uvicorn_run(config_file, args)
-        else:
-            run_args = formulate_run_args(image_type, image_name)
-
-            run_args.extend([str(args.port)])
-
-            if config_file:
-                run_args.extend(["--config", str(config_file)])
-
-            run_command(run_args)
+        self._uvicorn_run(config_file, args)
 
     def _uvicorn_run(self, config_file: Path | None, args: argparse.Namespace) -> None:
         if not config_file: