test: use uv when starting server

# What does this PR do?


## Test Plan

tests/integration/fixtures/common.py

@@ -6,6 +6,7 @@
 
 import inspect
 import os
+import shlex
 import signal
 import socket
 import subprocess
@@ -38,10 +39,10 @@ def is_port_available(port: int, host: str = "localhost") -> bool:
 
 def start_llama_stack_server(config_name: str) -> subprocess.Popen:
     """Start a llama stack server with the given config."""
-    cmd = ["llama", "stack", "run", config_name]
+    cmd = f"uv run --with llama-stack llama stack build --template {config_name} --image-type venv --run"
     devnull = open(os.devnull, "w")
     process = subprocess.Popen(
-        cmd,
+        shlex.split(cmd),
         stdout=devnull,  # redirect stdout to devnull to prevent deadlock
         stderr=subprocess.PIPE,  # keep stderr to see errors
         text=True,