[TASK] Remove upgrade wizards from TYPO3 6 to 7

Remove upgrade wizards for upgrading from TYPO3 v6 to v7.

Resolves: #80911
Releases: master
Change-Id: I1337341150050da971221fafaca4548dfec3bd4c
Reviewed-on: https://review.typo3.org/52514


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>