[TASK] Remove `doctrine/dbal` version aware method mocking in tests

`\TYPO3\CMS\Core\Tests\Unit\Database\ConnectionTest` containes
code to mock Connection methods conditionally, based on their
existance surrounded by a `@todo` comment to remove this, when
`doctrine/dbal` has been required with 2.11.0 as minimal version.

The version raise has been done already a long time ago, however
the removal of this conditional test mock has been missed.

This change removes the conditional mocking now.

Resolves: #103929
Releases: main, 12.4, 11.5
Change-Id: I4cc2d5942149f69e044c25379c82388f1c4b9f45
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84423


Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>