chore!: remove --env from llama stack run (#3711)

# What does this PR do?
user can simply set env vars in the beginning of the command.`FOO=BAR
llama stack run ...`

## Test Plan
Run
TELEMETRY_SINKS=coneol uv run --with llama-stack llama stack build
--distro=starter --image-type=venv --run




---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with
[ReviewStack](https://reviewstack.dev/llamastack/llama-stack/pull/3711).
* #3714
* __->__ #3711

llama_stack/core/start_stack.sh

@@ -25,7 +25,7 @@ error_handler() {
 trap 'error_handler ${LINENO}' ERR
 
 if [ $# -lt 3 ]; then
-  echo "Usage: $0 <env_type> <env_path_or_name> <port> [--config <yaml_config>] [--env KEY=VALUE]..."
+  echo "Usage: $0 <env_type> <env_path_or_name> <port> [--config <yaml_config>]"
   exit 1
 fi
 
@@ -43,7 +43,6 @@ SCRIPT_DIR=$(dirname "$(readlink -f "$0")")
 
 # Initialize variables
 yaml_config=""
-env_vars=""
 other_args=""
 
 # Process remaining arguments
@@ -58,15 +57,6 @@ while [[ $# -gt 0 ]]; do
         exit 1
       fi
       ;;
-    --env)
-      if [[ -n "$2" ]]; then
-        env_vars="$env_vars --env $2"
-        shift 2
-      else
-        echo -e "${RED}Error: --env requires a KEY=VALUE argument${NC}" >&2
-        exit 1
-      fi
-      ;;
     *)
       other_args="$other_args $1"
       shift
@@ -119,7 +109,6 @@ if [[ "$env_type" == "venv" ]]; then
     llama stack run \
     $yaml_config_arg \
     --port "$port" \
-    $env_vars \
     $other_args
 elif [[ "$env_type" == "container" ]]; then
     echo -e "${RED}Warning: Llama Stack no longer supports running Containers via the 'llama stack run' command.${NC}"