[Backport] Removed unused interface reference

[mage2pratik]

Original Pull Request

#16932
Removed unused interface reference

Description

The interface Magento\Framework\Indexer\StateInterface is not being used in this class, so its reference declaration is not necessary

Fixed Issues (if relevant)

Improvement

Manual testing scenarios

N/A

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)

[orlangur]

@mage2pratik such manual change is not really needed as can be done with php-cs-fixer all over the code automatically and will be done in near future.