[Backport] Solved swagger response of product attribute option is_default

[mage2pratik]

Original Pull Request

#20913

Fixed Issues (if relevant)

1. Incorrect Swager Definition for eav-data-attribute-option-interface  #18525: Incorrect Swager Definition for eav-data-attribute-option-interface

Manual testing scenarios (*)

Example : https://MAGENTO-HOST-NAME/rest/all/V1/products/attributes/country_of_manufacture
For above example URL it will give "is_default": true for the default selected country

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @mage2pratik. Thank you for your contribution
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[magento-engcom-team]

Hi @sidolov, thank you for the review.
ENGCOM-4234 has been created to process this Pull Request

[ghost]

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