Disable "Window is Ready" Notification in Gnome Shell?

gsettings set org.gnome.desktop.wm.preferences auto-raise 'true'

For anyone viewing this question recently, and willing to accept the newly opened window to rise on top of other open windows.

The answer I arrived at is to install this Gnome Extension:

https://extensions.gnome.org/extension/1007/window-is-ready-notification-remover/

Discovered while participating in this issue:

https://github.com/signalapp/Signal-Desktop/issues/3321

There is a gnome shell extension called Steal my Focus which disables this behavior but it doesn't seem to be supported by the developer anymore. You can make it work though by forking the git repository, editing the metadata.json file and adding your gnome-shell version in there. Here is mine:

{
    "_generated": "Generated by SweetTooth, do not edit",
    "description": "Let windows steal focus. Removes the annoying 'Window is ready' notification and focus window immediately",
    "name": "Steal My Focus",
    "original-authors": [
         "kagesenshi.87@gmail.com"
    ],
    "shell-version": [
         "3.2","3.5.2","3.6","3.6.2","3.7","3.8","3.10","3.10.1"
    ],
    "url": "https://github.com/kagesenshi/gnome-shell-extension-stealmyfocus",
    "uuid": "steal-my-focus@kagesenshi.org",
    "version": 1
}

In Gnome 3.18, there is an option in gnome-tweak-tool to automatically focus on the window instead of displaying this annoying notifications.