[TASK] Raise the number of possible file- and dbmounts from 10 to 25

The limitation of 10 dbmounts and filemounts does not work in each
installation. Due to the fact that removing the limits completely would
most likely waste quite some space in most installations, we agreed to
have equal limits everywhere and raise the limits to 25.

Change-Id: I60f84b5b9e03661c19840ec711533be207966ae3
Fixes: #30926
Releases: 4.6
Reviewed-on: http://review.typo3.org/6271
Reviewed-by: Steffen Gebert
Tested-by: Steffen Gebert