UI: Unset bandwidth test on non-Twitch service / disconnect

For additional safety, uncheck the bandwidth test checkbox so that the
setting isn't persisted in an enabled state when disconnecting or
switching a service. Also just straight up disable if not authed to
Twitch when saving settings.

UI/window-basic-settings-stream.cpp

@@ -177,9 +177,6 @@ void OBSBasicSettings::SaveStream1Settings()
 		}
 	}
 
-	obs_data_set_bool(settings, "bwtest",
-			  ui->bandwidthTestEnable->isChecked());
-
 	if (!!auth && strcmp(auth->service(), "Twitch") == 0) {
 		bool choiceExists = config_has_user_value(
 			main->Config(), "Twitch", "AddonChoice");
@@ -192,6 +189,11 @@ void OBSBasicSettings::SaveStream1Settings()
 
 		if (choiceExists && currentChoice != newChoice)
 			forceAuthReload = true;
+
+		obs_data_set_bool(settings, "bwtest",
+				  ui->bandwidthTestEnable->isChecked());
+	} else {
+		obs_data_set_bool(settings, "bwtest", false);
 	}
 
 	obs_data_set_string(settings, "key", QT_TO_UTF8(ui->key->text()));
@@ -470,6 +472,8 @@ void OBSBasicSettings::OnOAuthStreamKeyConnected()
 			ui->bandwidthTestEnable->setVisible(true);
 			ui->twitchAddonLabel->setVisible(true);
 			ui->twitchAddonDropdown->setVisible(true);
+		} else {
+			ui->bandwidthTestEnable->setChecked(false);
 		}
 	}
 
@@ -530,6 +534,8 @@ void OBSBasicSettings::on_disconnectAccount_clicked()
 	OAuth::DeleteCookies(service);
 #endif
 
+	ui->bandwidthTestEnable->setChecked(false);
+
 	ui->streamKeyWidget->setVisible(true);
 	ui->streamKeyLabel->setVisible(true);
 	ui->connectAccount2->setVisible(true);