Clean up inconsistent 3-legged error scenarios and applicability notes in Device Identifier ATP

[albertoramosmonagas]

Problem description

Some ATP scenarios in the Device Identifier repository appear to be inconsistent with the API semantics for 2-legged vs 3-legged flows and introduce ambiguity for implementers.

In particular:

• The scenarios @DeviceIdentifier_retrieveIdentifier_422.4_device_token_mismatch, @DeviceIdentifier_retrievePPID_422.4_device_token_mismatch, and @DeviceIdentifier_retrieveType_422.4_device_token_mismatch do not seem to provide meaningful additional coverage. In 3-legged flows, the device object must not be provided, so the expected outcome should already be 422 UNNECESSARY_IDENTIFIER, regardless of whether the supplied device matches or mismatches the token subject.
• Several ATP comments use the word "typically" to indicate whether a scenario applies to 2-legged or 3-legged tokens. This wording is too weak for behavior that is effectively mandatory and may create confusion for implementers.
• The scenario @DeviceIdentifier_retrievePPID_422.1_device_identifiers_unsupported is not clearly marked as a 2-legged-only case, although unsupported device identifiers are only relevant when the request depends on an explicit device selector.
• There may also be some partial overlap in certain schema-validation scenarios, although that should only be addressed if a broader cleanup of negative validation coverage is planned.

Expected action

• Remove or merge the three 422.4_device_token_mismatch scenarios into the existing UNNECESSARY_IDENTIFIER coverage.
• Replace "typically" wording with explicit applicability wording for 2-legged and 3-legged scenarios.
• Mark @DeviceIdentifier_retrievePPID_422.1_device_identifiers_unsupported as a 2-legged-only scenario, or clarify this explicitly in the scenario comments.
• Optionally review overlapping schema-validation scenarios only if a broader ATP refactor is considered worthwhile.

Additional context

Relevant API semantics:

• With a 2-legged token, the subject must be identified through the device object.
• With a 3-legged token, the device object must not be included.
• If a 3-legged token is used and the device object is still provided, the expected error is 422 UNNECESSARY_IDENTIFIER.

This issue is intended as a targeted ATP consistency cleanup, not as a broader restructuring of naming conventions, shared scenario layout, or legacy test asset conventions.