Run glob queries separately to allow query optimizer more efficiency
Created by: davecromberge
Addresses https://github.com/dalmatinerdb/dqe_idx_pg/issues/12,
An alternative approach would be to run each glob from the frontend grafana source against multiple DFE nodes, to allow some concurrency gains over the approach in this PR. However, this does put an implicit contract on the client which makes the approach in this pull request more attractive.