[Forwardport] small optimization in if-condition

[mzeis]

Original Pull Request

#15002

Description

There is no needs to cast $value to bool in runtime because it have value === '' by if-condition above

Fixed Issues (if relevant)

Not relevant.

Manual testing scenarios

Not relevant.

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]

@mzeis thank you for contributing. Please accept Community Contributors team invitation here to gain extended permissions for this repository.

[magento-engcom-team]

Hi @mzeis. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.3.0 release.