Temporarily remove terms using obsolete GO aging process

This commit intends to provide a short term fix for the issues caused by the obsoletion of the process term [aging GO:0007568](geneontology/go-announcements#502).
Need to add back these terms once there are appropriate replacement terms for [GO:0007568](https://www.ebi.ac.uk/ols/ontologies/GO/terms?iri=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FGO_0007568). See related issue #239.