[LEAKED DISPOSABLE]: selectbox custom markdown

[bpasero]

At:

vscode/src/vs/base/browser/ui/selectBox/selectBoxCustom.ts

Line 886 in 2b7ad1a

const rendered = renderMarkdown({ value: text, supportThemeIcons: true }, { actionHandler });

The rendered markdown needs to be disposed, maybe right after?

Came in from #160498