[JS] Remove deprecated generate behavior.

[Retribution98]

Description

Since version 2026.0.0, LLMPipeline.generate() returns DecodedResults by default.
To get a string representation, call the toString() method on DecodedResults.

CVS-176152

Checklist:

• Tests have been updated or added to cover the new code.
• This patch fully addresses the ticket.
• I have made corresponding changes to the documentation.

[Copilot]

Pull request overview

This PR removes deprecated behavior from the JavaScript bindings where LLMPipeline.generate() could optionally return a string. Since version 2026.0.0, the method now consistently returns DecodedResults objects, requiring users to call toString() for string representations.

Key Changes:

• Removed the return_decoded_results configuration option and related deprecation warnings
• Updated all test cases to expect DecodedResults objects instead of strings
• Cleaned up type definitions to remove the deprecated config option

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/js/lib/pipelines/llmPipeline.ts	Removed conditional logic for return_decoded_results flag and deprecation warning
src/js/lib/utils.ts	Removed DecodedResultsConfig type definition and its usage in GenerationConfig
src/js/tests/module.test.js	Updated test assertions to expect DecodedResults objects and removed tests for deprecated string return behavior
src/js/tests/structuredOutput.test.js	Removed return_decoded_results: true from all test generation configs
src/js/eslint.config.cjs	Removed return_decoded_results from the allowed snake_case identifiers list

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.

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[almilosz]

Are any changes necessary for openvino-langchain?

[Retribution98]

Are any changes necessary for openvino-langchain?

Yes, changes will be needed after the release of the major version of OV and the update of the openvino-langchain to use it. Until then, it will work correctly.