bug: NavController.navigateRoot does not clear navigation stack

# Bug Report

**Ionic version:**

[ ] **4.x**
[x] **5.x**

**Current behavior:**

Call `NavController.navigateRoot` and you can still navigate back to the previous page using the browser back button.

**Expected behavior:**

"Going root means that all existing pages in the stack will be removed, and the navigated page will become the single page in the stack."

**Steps to reproduce:**

Call the method mentioned above using angular 11 and ionic 5 and see that it does not do the needful.

**Other information:**

**Ionic info:**

```
Ionic:

Ionic CLI : 5.4.16 (/Users/derek.rtp/.npm/_npx/65454/lib/node_modules/ionic)
Ionic Framework : @ionic/angular 5.5.2
@angular-devkit/build-angular : 0.1100.6
@angular-devkit/schematics : 11.0.1
@angular/cli : 11.0.6
@ionic/angular-toolkit : 2.3.3

Utility:

cordova-res : not installed
native-run : not installed

System:

NodeJS : v14.7.0 (/usr/local/Cellar/node/14.7.0/bin/node)
npm : 6.14.11
OS : macOS Catalina
```