chore!: remove --image-type and --image-name from llama stack run (#3714)

# What does this PR do?
Simplifies the CLI. I don't think these options make sense anymore: only
venv is supported as image-type, and users can simply activate the env
before running `llama stack` as they do any other project.

## Test Plan





---
[//]: # (BEGIN SAPLING FOOTER)
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* __->__ #3714
* #3711

scripts/integration-tests.sh

@@ -186,7 +186,7 @@ if [[ "$STACK_CONFIG" == *"server:"* ]]; then
         echo "Llama Stack Server is already running, skipping start"
     else
         echo "=== Starting Llama Stack Server ==="
-        nohup llama stack run ci-tests --image-type venv > server.log 2>&1 &
+        nohup llama stack run ci-tests > server.log 2>&1 &
 
         echo "Waiting for Llama Stack Server to start..."
         for i in {1..30}; do