add missing europe geocodes

[attwad]

I had missed about a thousand geocodes that were added to the europe spreadsheet after the introduction of the geo_admin.tsv file. Kudos to TR for letting me know.

• Only keep unique rows in geo_admin.tsv
• Admin ids are now absent from the tsv file as it doesn't make sense to have it there anymore

[tbrewer-healthmap]

Thanks Timothé!