[TASK] Fix typos in upgrade wizards of Install Tool

Use the term "Upgrade wizard" instead of "Update wizard"
for the buttons of the single steps as the main menu item
is also called "Upgrade wizard".

Resolves: #81383
Releases: master, 8.7
Change-Id: I8047ae45101533a67fa4488af7040acc49af563f
Reviewed-on: https://review.typo3.org/52973


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Elmar Hinz <t3elmar@gmail.com>
Reviewed-by: Thomas Hohn <thomas@hohn.dk>
Tested-by: Thomas Hohn <thomas@hohn.dk>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>