fix issue with k8s_job_op when combining command and container_config (…

…#11713)

Summary:
You can't add a key to an immutable dict.

Test Plan: New test case

### Summary & Motivation

### How I Tested These Changes

integration_tests/test_suites/k8s-test-suite/tests/test_k8s_job_op.py

@@ -190,3 +190,28 @@ def with_config_job():
     job_name = get_k8s_job_name(run_id, with_container_config.name)
 
     assert "SHELL_FROM_CONTAINER_CONFIG" in _get_pod_logs(cluster_provider, job_name, namespace)
+
+
+@pytest.mark.default
+def test_k8s_job_op_with_container_config_and_command(namespace, cluster_provider):
+    with_container_config = k8s_job_op.configured(
+        {
+            "image": "busybox",
+            "container_config": {"command": ["echo", "SHELL_FROM_CONTAINER_CONFIG"]},
+            "namespace": namespace,
+            "load_incluster_config": False,
+            "kubeconfig_file": cluster_provider.kubeconfig_file,
+            "command": ["echo", "OVERRIDES_CONTAINER_CONFIG"],
+        },
+        name="with_container_config",
+    )
+
+    @job
+    def with_config_job():
+        with_container_config()
+
+    execute_result = with_config_job.execute_in_process()
+    run_id = execute_result.dagster_run.run_id
+    job_name = get_k8s_job_name(run_id, with_container_config.name)
+
+    assert "OVERRIDES_CONTAINER_CONFIG" in _get_pod_logs(cluster_provider, job_name, namespace)

python_modules/libraries/dagster-k8s/dagster_k8s/ops/k8s_job_op.py

@@ -203,7 +203,7 @@ def execute_k8s_job(
         else None,
     )
 
-    container_config = container_config or {}
+    container_config = container_config.copy() if container_config else {}
     if command:
         container_config["command"] = command