remove the outdated Deduplication section

Deduplication section appears to be describing how things worked prior to nodejs/node#22842, so is no longer correct. The output in 11.12 is 

```
setImmediate 1
process.nextTick a
process.nextTick b
setImmediate 2
process.nextTick a
process.nextTick b
```

Author: bughit

locale/en/docs/guides/event-loop-timers-and-nexttick.md

@@ -398,56 +398,6 @@ To get around this, the `'listening'` event is queued in a `nextTick()`
 to allow the script to run to completion. This allows the user to set
 any event handlers they want.
 
-### Deduplication
-
-For the `timers` and `check` phases, there is a single transition 
-between C to JavaScript for multiple immediates and timers. This deduplication
-is a form of optimization, which may produce some unexpected side effects.
-Take this code snippet as an example:
-
-```js
-// dedup.js
-const foo = [1, 2];
-const bar = ['a', 'b'];
-
-foo.forEach(num => {
-  setImmediate(() => {
-    console.log('setImmediate', num);
-    bar.forEach(char => {
-      process.nextTick(() => {
-        console.log('process.nextTick', char);
-      });
-    });
-  });
-});
-```
-```bash
-$ node dedup.js
-setImmediate 1
-setImmediate 2
-process.nextTick a
-process.nextTick b
-process.nextTick a
-process.nextTick b
-```
-
-The main thread adds two `setImmediate()` events, which when processed
-will add two `process.nextTick()` events. When the event loop reaches
-the `check` phase, it sees that there are currently two events created by
-`setImmediate()`. The first event is grabbed and processed, which prints
-and adds two events to the `nextTickQueue`.
-
-Because of deduplication, the event loop does not transition back to the
-C/C++ layer to check if there are items in the `nextTickQueue` immediately. It
-instead continues to process any remaining `setImmediate()` events, of which
-one currently remains. After processing this event, two more events are 
-added to the `nextTickQueue` for a total of four events.
-
-At this point, all previously added `setImmediate()` events have been processed.
-The `nextTickQueue` is now checked, and events are processed in FIFO order. When
-this `nextTickQueue` is emptied, the event loop considers all operations to have 
-been completed for the current phase and transitions to the next phase.
-
 ## `process.nextTick()` vs `setImmediate()`
 
 We have two calls that are similar as far as users are concerned, but