Unconfigured context causes repeated build failures

Setting context: org-global in workflows before the organization has configured their first context repeatably causes “Looks like we had a bug in our infrastructure…”. Removing the key seems to fix it.

See https://circleci.com/workflow-run/cc73029b-29fd-4b6c-85c6-3e9802d14fca (failure) and https://circleci.com/workflow-run/129026a5-2c0b-4bfd-ae66-e6570e7ae1f9 (success).