Upload AOI modal does not clear uploaded data

After successfully uploading an AOI, clicking the "Upload AOI GeoJSON" button simply displays the information from my last uploaded AOI, and doesn't permit upload of new files. I should be able to upload a new AOI instead.

Start by reproducing the issue with the “Upload AOI GeoJSON” button, then locate the frontend modal and upload handler responsible for retaining the previous AOI data. Confirm that selecting the button after a successful upload allows a new file to be chosen and that the old upload information is cleared.

Written by the indexing model from the issue text.