[24.0] Fix workflow run form for workflows with null rename PJA

[mvdbeek]

Fixes:

AttributeError: 'NoneType' object has no attribute 'values'
  File "galaxy/web/framework/decorators.py", line 346, in decorator
    rval = func(self, trans, *args, **kwargs)
  File "galaxy/webapps/galaxy/api/workflows.py", line 357, in workflow_dict
    ret_dict = self.workflow_contents_manager.workflow_to_dict(
  File "galaxy/managers/workflows.py", line 907, in workflow_to_dict
    wf_dict = self._workflow_to_dict_run(trans, stored, workflow=workflow, history=history or trans.history)
  File "galaxy/managers/workflows.py", line 1025, in _workflow_to_dict_run
    step_model["replacement_parameters"] = step.module.get_informal_replacement_parameters(step)
  File "galaxy/workflow/modules.py", line 2388, in get_informal_replacement_parameters
    for argument in pja.action_arguments.values():

from https://sentry.galaxyproject.org/share/issue/954ebe7b658f401a8a8e40987d43a91d/

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