🚀 [Feature][Webapp] Set Chat Room List Search Bar Placeholder to Customer Text

Created by: Elweyn

🚀 Feature

The default text of the search bar makes it seem that we can search people of the network. Would be great to change the default text to Vorhandene Chat-Räume filtern

🤖 ToDo

• Change the default text to Vorhandene Chat-Räume filtern