a) Configuring
Set the value “[]” on app-picker-layout of org.gnome.shell in the dconf configuration database.
gsettings set org.gnome.shell app-picker-layout "[]"
You can also do it in the graphical way instead of the command line by using a GUI application named dconf-editor.
b) Restarting
Restart your cute GNOME shell by logging out and then logging in. Or you can simply restart your lovely system.
Then you will find your GNOME‘s App Picker sorting the entries alphabetically every time.