Fix registry key in End to End test

This was introduced in some previous PR, but we didn't notice because
our CI is broken.

end-to-end/organization_token_test.go

@@ -100,6 +100,6 @@ func activateOrgSubscription(t *testing.T) {
 	require.NoErrorf(t, err, "Setup: could not open UbuntuPro registry key")
 	defer key.Close()
 
-	err = key.SetStringValue("ProTokenOrg", token)
+	err = key.SetStringValue("UbuntuProToken", token)
 	require.NoError(t, err, "could not write token in registry")
 }