Autocomplete: previous selections are highlighted darker

[kara]

Unlike selects, autocompletes shouldn't remember previous selections. This is probably a side effect of #6302 because of code sharing between the autocomplete and the select.

To repro:

1. Select an autocomplete option (let's say "Arizona").
2. Delete all the letters from "Arizona" until only "A" is left
3. Navigate to the third option using the keyboard. On focus, it's highlight is darker than the others.

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