Replace Listbox in Create Disk side modal with Combobox

[charliepark]

I was working on #2776 and noticed that — once alphabetizing the mock API responses — some of the tests failed. It seems that our ListboxField component has a cap on results, and, when selecting a snapshot, some of the snapshots were no longer available.

I haven't looked into this, but would hope that by using a combobox there we could let the user filter for the desired snapshot name.

[septum]

Hi! Can I help out with this?

[david-crespo]

I would be surprised if there is a cap on the number of items in listbox — seems more likely something else is going on. A combobox is more appropriate here regardless.

@septum sure, but see CONTRIBUTING.md: you're welcome to give a try, but please keep it simple and don't take it personally if we don't have time to merge it quickly.

[septum]

Understood, thanks for letting me contribute.