Improve backoffice category display performance

[Dnd-Mafer]

This PR improvement performance of categroy display in BO. It fixes #39829

Description

This PR change a time consuming subselect in SQL query for a fast join.

Fixed Issues

Fixes #39829

Manual testing scenarios

Connect to BO
Go on Catalog -> Category
Check that numbers in parenthesis near category names are corresponding to number of category products

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• 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)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

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[Dnd-Mafer]

@magento run all tests