remove extranious selector that prevents matching issues

[mattip]

Restarting a migration will fail to recognize existing github issues since the selector is looking for labels. Removing that enables the correct behaviour.

[mattip]

One thing I noted when restarting a partial import. If the process created an issue but was interrupted before finishing the issue import, restarting the import will not match the partial import and will create a new issue. This "messes up" the issue numbering.