test: always start a new server in integration-tests.sh (#4050)

# What does this PR do?
This prevents interference from already running servers, and allows
multiple concurrent integration test runs. Unleash the AIs!

## Test Plan
start a LS server at port 8321

Then observe test uses port 8322:

❯ uv run --no-sync ./scripts/integration-tests.sh --stack-config
server:ci-tests --inference-mode replay --setup ollama --suite base
--pattern '(telemetry or safety)'
=== Llama Stack Integration Test Runner ===
Stack Config: server:ci-tests
Setup: ollama
Inference Mode: replay
Test Suite: base
Test Subdirs:
Test Pattern: (telemetry or safety)

Checking llama packages
llama-stack 0.4.0.dev0 /Users/erichuang/projects/new_test_server
llama-stack-client                       0.3.0
ollama                                   0.6.0
=== Applying Setup Environment Variables ===
Setting SQLITE_STORE_DIR:
/var/folders/cz/vyh7y1d11xg881lsxsshnc5c0000gn/T/tmp.bKLsaVAxyU
Setting stack config type: server
Setting up environment variables:
export OLLAMA_URL='http://0.0.0.0:11434'
export SAFETY_MODEL='ollama/llama-guard3:1b'

Will use port: 8322
=== Starting Llama Stack Server ===
Waiting for Llama Stack Server to start on port 8322...
✅ Llama Stack Server started successfully

.github/workflows/integration-tests.yml

@@ -22,6 +22,7 @@ on:
       - '.github/actions/setup-ollama/action.yml'
       - '.github/actions/setup-test-environment/action.yml'
       - '.github/actions/run-and-record-tests/action.yml'
+      - 'scripts/integration-tests.sh'
   schedule:
     # If changing the cron schedule, update the provider in the test-matrix job
     - cron: '0 0 * * *'  # (test latest client) Daily at 12 AM UTC