fix(test): Remove stale Kafka container before startup

Always remove the named Kafka system-test container before starting a new broker. This avoids docker name conflicts after crashed or interrupted runs while still keeping stop_kafka_broker ownership-aware for reused brokers.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: adinauer

test/system-test-runner.py

@@ -227,13 +227,21 @@ def wait_for_port(self, host: str, port: int, max_attempts: int = 20) -> bool:
                 time.sleep(1)
         return False
 
+    def remove_kafka_broker_container(self) -> None:
+        subprocess.run(
+            ["docker", "rm", "-f", KAFKA_CONTAINER_NAME],
+            check=False,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
+
     def start_kafka_broker(self) -> None:
         if self.wait_for_port("localhost", 9092, max_attempts=1):
             print("Kafka broker already running on localhost:9092, reusing it.")
             self.kafka_started_by_runner = False
             return
 
-        self.stop_kafka_broker()
+        self.remove_kafka_broker_container()
 
         print("Starting Kafka broker (Redpanda) for system tests...")
         run_result = subprocess.run(
@@ -280,12 +288,7 @@ def stop_kafka_broker(self) -> None:
         if not self.kafka_started_by_runner:
             return
 
-        subprocess.run(
-            ["docker", "rm", "-f", KAFKA_CONTAINER_NAME],
-            check=False,
-            stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL,
-        )
+        self.remove_kafka_broker_container()
         self.kafka_started_by_runner = False
 
     def start_sentry_mock_server(self) -> None: