Localization issue about scroll bar context menu in Simplified Chinese

[kingcean]

• .NET Core Version: ALL.
• Windows version: all.
• Does the bug reproduce also in WPF for .NET Framework 4.8?: No
• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? No.
• Security issues and bugs should be reported privately, learn more via our [responsible disclosure guidelines]. No.

Problem description:
The context menu of scroll bar in Simplified Chinese includes some menu items in English and incorrect Simplified Chinese.

Menu item	Current implementation	Expected
Scroll here	滚动至此	滚动至此
Top	Top	顶部
Bottom	底	底部
Page Up	Page Up	向上翻页
Page Down	Page Down	向下翻页
Scroll Up	向上滚动	向上滚动
Scroll Down	向下滚动	向下滚动

Actual behavior:

Following sample targets .NET Core App 3.1 which is incorrect.

Expected behavior:

Following sample targets .NET Framework 4.6 which is correct.

Minimal repro:

1. Create a WPF project.
2. Insert a ScrollViewer.
3. Run and right click on the scroll bar.

Required Simplified Chinese environment.

[ryalanms]

@cristianosuzuki77: Could you take a look at this one? Thanks.

[iamartyom]

I added fix for this in #4407 pr.
Please check.