There are multiple ways of doing so, here's one of them:
$(document).on("submit", function(e) {
if (e.target.id == "mw-upload-form") {
$(e.target).find('[name="wpLicense"] [value=""]:not([disabled])').attr("value", "TEMPLATENAME");
}
});
Put it in your personal wikia.js or global.js, and replace TEMPLATENAME with the name of that licensing template in a given wiki (without the Template: prefix). This particular scripts adds the licensing the moment you press the "Upload" button, though it's also possible to make it change the licensing dropdown's default text, which doesn't actually affect the licensing itself.
Just remember to remove/comment it out from your js page when you no longer need it.