refactor: remove redundant Builder.samples() method in StabilityAiImageOptions

[JHZLO]

Summary

This PR removes the samples(Integer samples) method from the StabilityAiImageOptions.Builder class, as it duplicates the existing N(Integer n) method.

Motivation

• Both samples() and N() internally call setN(), which sets the same field (samples JSON property).
• Having both methods introduces unnecessary redundancy and may cause confusion for users.
• N() is already consistent with the ImageOptions.getN() interface method and commonly used throughout the codebase.

Additional Notes

If needed, developers can still set the samples value using the N() method:

StabilityAiImageOptions options = StabilityAiImageOptions.builder()
    .N(3)
    .build();