bug: ios native refresher overlaps content when hiding

# Bug Report

It ***MAY*** be related to #21291, if so pls close. But the behaviour is different, so i'm opening it to be sure

**Ionic version:**

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

**Current behavior:**

Please have a look into the attached video:
1. When the content (list in this case) changes/ is reassigned while refreshing the content kind of jumps to the top and back.
2. When the refresher is refreshing and i scroll up again, the spinner hides to late and don't hide behind the content. I think it is overlayed by the content in native ios (see at the end of the video)

**Expected behavior:**

1. to not happen^^
2. to hide the spinner behind the content when scrolling up

**Reproduction / Video:**

Video: [Uploaded here](https://gofile.io/d/N4Aca7)

Repo of the App seen in the video: https://github.com/EinfachHans/ion-refresher-bug2

**Other information:**

**Ionic info (of the test repo):**

```
Ionic CLI : 6.12.0 (/usr/local/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 5.4.0
@angular-devkit/build-angular : 0.1000.8
@angular-devkit/schematics : 10.0.8
@angular/cli : 10.0.8
@ionic/angular-toolkit : 2.3.3

Cordova:

Cordova CLI : 10.0.0
Cordova Platforms : ios 6.1.1
Cordova Plugins : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.2.1, (and 4 other plugins)

Utility:

cordova-res : 0.15.1
native-run (update available: 1.2.2) : 1.0.0

System:

Android SDK Tools : 25.2.3 (/Users/hanskrywalsky/Library/Android/sdk)
ios-deploy : 1.10.0
ios-sim : 8.0.2
NodeJS : v12.18.3 (/usr/local/bin/node)
npm : 6.14.8
OS : macOS Catalina
Xcode : Xcode 12.0.1 Build version 12A7300
```

Start with the linked reproduction repository and the uploaded video to reproduce the native iOS refresher behavior. Inspect the refresher implementation and its scrolling behavior for the two reported symptoms: content jumping during refresh and the spinner remaining over content. Done means both behaviors no longer occur.

由索引模型根据 Issue 内容生成。