[TASK] Remove inline JavaScript from Install Tool

Removes inline JavaScript from installer step
"Create Administrative User & Specify Site Name".

Also mark button as type="button" to avoid intercepting
the form submit due to the toggling event handler.

Resolves: #95266
Resolves: #95241
Releases: master
Change-Id: I002fabc185bf8fdf88793abfdf6ca89b61847e3f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71121


Tested-by: Simon Gilli <typo3@gilbertsoft.org>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Simon Gilli <typo3@gilbertsoft.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>