DEFINE inside workflow files are problematic

[berland]

If you have a file wflow containing:

DEFINE <FOO> defined_in_workflow

and LOAD_WORKFLOW wflow in your config file, then there will be no errors, but it will not be substituted in e.g.:

RUNPATH poly_out/realization-<FOO>-<IENS>/iter-<ITER>

If you also in your config file do

DEFINE <FOO> first_foo
then Ert will crash with

2025-03-03 15:56:50,096 - ert.__main__ - MainThread - ERROR - ERT crashed unexpectedly with "'tuple' object does not support item assignment"
Traceback (most recent call last):
  File "/data/projects/ert/src/ert/__main__.py", line 610, in main
    args.func(args, context.plugin_manager)
  File "/data/projects/ert/src/ert/cli/main.py", line 43, in run_cli
    ert_config = ErtConfig.with_plugins().from_file(args.config)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/ert_config.py", line 659, in from_file
    return cls.from_dict(user_config_dict)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/ert_config.py", line 742, in from_dict
    workflow_jobs, workflows, hooked_workflows = workflows_from_dict(
                                                 ^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/ert_config.py", line 348, in workflows_from_dict
    workflow = Workflow.from_file(
               ^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/workflow.py", line 93, in from_file
    cmd_list = cls._parse_command_list(
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/workflow.py", line 38, in _parse_command_list
    config_dict = parse(src_file, schema, pre_defines=context)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/parsing/lark_parser.py", line 497, in parse
    return _transform_tree(_parse_file(file), file, schema, pre_defines)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/parsing/lark_parser.py", line 535, in _transform_tree
    return _tree_to_dict(
           ^^^^^^^^^^^^^^
  File "/data/projects/ert/src/ert/config/parsing/lark_parser.py", line 208, in _tree_to_dict
    existing_define[1:] = define_args
    ~~~~~~~~~~~~~~~^^^^
TypeError: 'tuple' object does not support item assignment