width is inconsistent in nz-modal of nz-dropdown-menu when first hover and later hover

[CC2013]

Reproduction link

https://stackblitz.com/edit/angular-nzdropdown-issue

Steps to reproduce

1.click the "click modal" button；
2.first hover "add config", the menu shows;
3.again hover "add config"， the menu shows again；

What is expected?

no matter hover any times, the drop menu's width would be inconsistent;

What is actually happening?

hover twice, but the drop menu's width is inconsistent;

Environment	Info
ng-zorro-antd	8.2.1
Browser	Chrome 76

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just the first time hover, the width has some problem. And I think it still a problem in the version 8.3.0

[hsuanxyz]

Work on v10, https://stackblitz.com/edit/angular-7qcaal?file=src%2Fapp%2Fapp.component.ts.

Please file a new issue or discussion if you are encountering a similar or related problem.