drop SIMPLE_UPDATE_MODE, limit housekeeping and updates to background processes

js/App.js

@@ -829,11 +829,6 @@ const App = {
 
          Headlines.initScrollHandler();
 
-         if (this.getInitParam("simple_update")) {
-            console.log("scheduling simple feed updater...");
-            window.setInterval(() => { Feeds.updateRandom() }, 30 * 1000);
-         }
-
          if (this.getInitParam('check_for_updates')) {
             window.setInterval(() => {
                this.checkForUpdates();

js/Feeds.js

@@ -743,13 +743,6 @@ const	Feeds = {
 		dialog.show();
 
 	},
-	updateRandom: function() {
-		console.log("in update_random_feed");
-
-		xhr.json("backend.php", {op: "RPC", method: "updaterandomfeed"}, () => {
-			//
-		});
-	},
 	renderIcon: function(feed_id, exists) {
 		const icon_url = App.getInitParam("icons_url") + '?' + dojo.objectToQuery({op: 'feed_icon', id: feed_id});