[Forwordport] fix: cache count() results for loops

[gelanivishal]

Original Pull Request

#15507

Description

This improves the performance of a few loops which were runningcount() in every iteration.

Fixed Issues (if relevant)

Manual testing scenarios

1. ...
2. ...

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

Hi @VladimirZaets, thank you for the review.
ENGCOM-2760 has been created to process this Pull Request

[orlangur]

Such change is not needed, check #16027 (comment) for more details.