Fix the signature validation tests in sentence-transformers suite

[BenWilson2]

Related Issues/PRs

#xxx

What changes are proposed in this pull request?

Adjust the signature validation within sentence-transformers test suite to conform to changes made in #9874

How is this PR tested?

• Existing unit/integration tests
• New unit/integration tests
• Manual tests

Does this PR require documentation update?

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• Yes. I've updated:
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[BenWilson2]

@serena-ruan please confirm that the behavior change reflected in this fix matches the behavior that you were intending in #9874 .
Previous behavior prior to that PR was to coerce the signature to a pandas DF mapping of columns from a List[str] input.

Question: Does the change in #9874 work as expected for model serving use cases with a defined schema for the following conditions:

1. Model is saved with an inferred signature based on a List[str] input example
2. Model is saved with default signature and a pd.DataFrame representation is submitted to serving (with different split formats)

[serena-ruan]

@serena-ruan please confirm that the behavior change reflected in this fix matches the behavior that you were intending in #9874 . Previous behavior prior to that PR was to coerce the signature to a pandas DF mapping of columns from a List[str] input.

Question: Does the change in #9874 work as expected for model serving use cases with a defined schema for the following conditions:

1. Model is saved with an inferred signature based on a List[str] input example
2. Model is saved with default signature and a pd.DataFrame representation is submitted to serving (with different split formats)

@BenWilson2 Yes, this fix matches the expected behavior in #9874, thanks! My test case contains a serving example for 1. For 2, it seems irrelevant to this change as the change only affects how we infer the signature?

[serena-ruan]

LGTM!

[BenWilson2]

@serena-ruan thank you for the validation :D