[DOCS] Streamline installation chapters of system extension manuals

The content of the installation chapter of the various system
extension differs, some don't have an installation chapter. This
is now streamlined: now every installation chapter has the
Composer-based installation and the legacy installation described
in the same way.

Resolves: #103308
Releases: main, 12.4
Change-Id: I7750ab3139e468a16c48e22a8e5659947713872a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83264


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Lina Wolf <112@linawolf.de>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Lina Wolf <112@linawolf.de>
Tested-by: Garvin Hicking <gh@faktor-e.de>