bug: Issues with ion-router-outlet and router-outlet

# Bug Report

**Ionic version:**

[x] **4.x**

**Current behavior:**

Navigation stops working when navigating from a tab to pages that use `router-outlet`.

Navigate to **Tab1** > **Page1** (contains `router-outlet`) > **Page2** (contains `router-outlet`) and then go back to Page1 and try to switch the tab. Navigation seems to stop working at that point. It appears the tabs are tying to use a nested router-outlet instead of the outlet at the root.

**Expected behavior:**

Deep navigation to pages from tabs that use `router-outlet` without navigation failing.

**Related Code**
Here is a repo of the issues using ion-router-outlet and router-outlet
https://github.com/tlaverdure/ion-router-outlet-test

**Ionic info:**

```
Ionic:

Ionic CLI : 5.2.2 (/usr/local/lib/node_modules/ionic)
Ionic Framework : @ionic/angular 4.6.2
@angular-devkit/build-angular : 0.13.9
@angular-devkit/schematics : 7.3.9
@angular/cli : 7.3.9
@ionic/angular-toolkit : 1.5.1

Utility:

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

System:

NodeJS : v12.1.0 (/usr/local/bin/node)
npm : 6.9.0
OS : macOS Mojave
```