Remove dead type-mismatched guard in airflow-ctl command generation

[rjgoyln]

_create_arg_for_non_primitive_type guarded the initialisation of
datamodels_extended_map with a condition that could never hold:

parameter_type_map = getattr(generated_datamodels, parameter_type)   # a Pydantic model class
if parameter_type_map not in self.datamodels_extended_map.keys():    # dict is keyed by model *name*

The map is keyed by the model name, so comparing the class object against
those keys is always True.

The dead guard turned out to be load-bearing. The field loop beneath it
appends unconditionally, so the always-taken reset was the only thing
keeping datamodels that several operations share — ConnectionBody
(3 operations), BackfillPostBody and VariableBody (2 each) — from
accumulating a duplicate copy of their fields on every visit. Repairing
the comparison to match the key type would therefore have introduced the
duplication rather than removed it (ConnectionBody expands to 27
entries instead of 9).

The guard is dropped in favour of the unconditional reset it was already
performing, so behaviour is unchanged and the intent is now honest.

Because the change is behaviour-preserving, the accompanying test passes
against both the old and the new code — it exists to fail against the
plausible-looking "fix" above, which is the trap this code invites. It
asserts the exact expected field list rather than merely the absence of
duplicates, so it also pins completeness and ordering.

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Opus 5)

Generated-by: Claude Code (Opus 5) following the guidelines