[BUGFIX] Update Wizard user input not taken into account

After reworking the install tool, the form element identifier was broken.

Resolves: #49258
Releases: 6.2
Change-Id: Ia9bae8c23345502ddbd4dd398f523af07dbfa5e1
Reviewed-on: https://review.typo3.org/21510
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn