Remove the spec file.

Now that datagrepper has passed package review and its spec file is kept in Fedora's git, there's really no need to keep a spec file in this "upstream" repo.

If we were to keep it here, we would have to update the spec file in two places when we make changes and they're likely to get out of sync.

This pull request is a proposal to drop this one and just keep the one in the Fedora Project git repo.