[TASK] Remove TYPO3_version switches

There is no need any more for TYPO3_version switches, which have been
here mostly to behave different for versions lower than 4.5.0, because
the compatible TYPO3 version in ext_emconf.php is set to 6.2.0 or
later.

Change-Id: I21ddf84dab201e9a1a9bf0808080d48e4aaae25a
Resolves: #59526
Releases: 2.0
Reviewed-on: https://review.typo3.org/30691
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler