Make Drupal 10 warning message more user friendly

The message can be changed/set to whatever the admin of the page wishes, but if we want to make the default value/configuration more user friendly like suggested, we need to make sure that the existing configuration also gets that change, that's why a post update hook was added. Leaving status to needs review, but from my POV, can be merged. (This change will also be present for at least D9.5)

The message on a new install is correctly set. Tested the update hook and it works correctly if it's the default message it gets changed and if it's not then it stays the same as the admin set it. This can be merged.

Automatically closed - issue fixed for 2 weeks with no activity.