Obviously damadam in the comments pointed to a more straightforward solution. You can change the keyboard combination directly under Settings - Keyboard, section "Navigation".
Below is the more "under the hood" approach which I first posted here. It allows you to have or keep multiple keyboard combinatons for the same action.
Open dconf-edit and change the keybindings for switch-applications from
['<Super>Tab', '<Alt>Tab'] to
['<Control>Tab']. You may need to install dconf-edit first because it is not installed by default.
Alternatively, you may use the terminal to change the setting:
gsettings set org.gnome.desktop.wm.keybindings switch-applications ['<Control>Tab']
To undo your changes from the terminal and reset to default, issue the command
gsettings reset org.gnome.desktop.wm.keybindings switch-applications