[ComboBox] Unexpected behavior when using combobox inside form

[alisonelizabeth]

I’m running into an issue with the EuiComboBox inside a <form>, where if I hit “enter” to select an option, it also tries to submit the form.

I believe this section of code needs to be updated to also call e.preventDefault() https://github.com/elastic/eui/blob/master/src/components/combo_box/combo_box.js#L389