[Backport 2.2] Use correct error message for duplicate error key in product import

[gelanivishal]

Original Pull Request

#15980

Description

During product CSV import, when a Url key duplicate is detected after the validation phase, the error message display only the error template but not the actual error details.
I have changed the addRowError() call using the detailed error message.

Fixed Issues (if relevant)

Manual testing scenarios

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)

Relates to

#15980

[magento-cicd2]

All committers have signed the CLA.

[magento-engcom-team]

Hi @gelanivishal. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me {$VERSION} instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[ishakhsuvarov]

Hi @gelanivishal
Please mention original Pull Request in the description when porting. This simplifies tracking of items which still require a port.

Thanks

[gelanivishal]

@ishakhsuvarov I have updated. Please check it.

Thank you.

[magento-engcom-team]

Hi @gelanivishal. Thank you for your contribution.
The changes from your Pull Request should be available with the upcoming 2.2.6 release.
Please check the release notes for final confirmation.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.