[TASK] Use strict comparison in BackendUserRepository

Since the demand object already uses strict types, it
is safe to use strict comparison when properties of the
demand object are used as operand.

Resolves: #98141
Releases: main
Change-Id: I6741c022f9d382416be6cab034d793fedfa35477
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75441


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>