[TASK] Allow more DB and File Mounts for BE users and BE groups

In big installations, more than just 25 DB mount points are needed.

Solution: Raise the default configuration to 100.

Releases: 6.2
Resolves: #55018
Change-Id: I613a90bc6c15b7642f2c6b6b6ca4ec8221838c0b
Reviewed-on: https://review.typo3.org/26834
Reviewed-by: Tom Ruether
Tested-by: Tom Ruether
Reviewed-by: Wouter Wolters
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer