Prevent closing dropdown view on scrollbar click.

[mmotyczynska]

Suggested merge commit message (convention)

Fix (ui): Dropdown view should not be closed when interacting with a scrollbar. Closes #14364.

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Additional information

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[niegowski]

You should disable native focus outline on focused dropdown panel, sth like here:

ckeditor5/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/toolbar/toolbar.css

Lines 109 to 111 in e8f4934

	&:focus {
	outline: none;
	}