[BUGFIX] Make default folder structure aware of 'web-dir' option

When having e.g. a composer-based installation in TYPO3 Core,
the install tool still generates the "wrong" folder structure in TYPO3.

When having e.g. "public" as subfolder where everything will
be installed, then the DefaultFactory should actually create
a /var/ folder (incl. /var/labels) and not keep the existing folder
structure (e.g. typo3temp/l10n).

Resolves: #89903
Releases: master, 9.5
Change-Id: Iaada837009be9e31dcb6969b1d424bf322841077
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63609


Tested-by: Susanne Moog <look@susi.dev>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>