Revert "Add missing institution-country associations for AR1 WGIII"

This reverts commit 79ff9686ebb00575ebc1c58549efe0a5664f8333.

I found a duplicate association of the same country and institution
with identifiers 1426 and 1427.

Related issue: #50
https://github.com/medea-project/ipcc-database/issues/50