[TASK] Avoid QueryBuilder::resetQueryPart() in ext:backend

Doctrine 4 will no longer provide access to SQL query parts,
so we need to adjust our internal usages to cope with this
change. The strategy by rule of thumb involves to not reuse
queryBuilder instances, so no reset must happen anyway.

Resolves: #100913
Releases: main
Change-Id: I663f1701eef78b4804cd800fdc131e2b1709ad64
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79137


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>