Fix duplicate --json-out-file parameter in prepare_memtier_benchmark_parameters

Author: fcostaoliveira

redis_benchmarks_specification/__self_contained_coordinator__/clients.py

@@ -7,8 +7,6 @@ def prepare_memtier_benchmark_parameters(
     oss_cluster_api_enabled,
 ):
     benchmark_command = [
-        "--json-out-file",
-        local_benchmark_output_filename,
         full_benchmark_path,
         "--json-out-file",
         local_benchmark_output_filename,