Remove description of additional setting in parenthesis in new Greeter

We can probably do without the description in parenthesis on the right of the names of the settings. If people don’t know what they are about we have more space and context in the configuration screen for the setting, and the current descriptions are probably too short to be helpful and only add noise (as segfault pointed out in a different way).

Parent Task: #10828 (closed)

Original created by @sajolida on 11437 (Redmine)