[select] Fix highlight being removed on popup mouseout when highlightItemOnHover is disabled

[atomiks]

• I have followed (at least) the PR section of the contributing guide.

Fixes the highlight being removed when leaving the popup due to the onPointerLeave handler. It should remain since it is sync'd only with the focus (keyboard) state.

https://stackblitz.com/edit/hqdzj2iz

Note: drag-to-select functionality when this prop is disabled currently does not work, WIP fix is in #3490.

[pkg-pr-new]

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@3492
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@3492
  

commit: 4a14355

[mui-bot]

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+45B(+0.01%)	🔺+2B(0.00%)

Details of bundle changes

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