ClusterInfo::get_epoch_slots_since scans the entire crds table to obtain
epoch-slots inserted since a timestamp:
https://github.com/solana-labs/solana/blob/013daa8f4/core/src/cluster_info.rs#L1245-L1262
The alternative is to index epoch-slots in crds table ordered by their
insert timestamp.
(cherry picked from commit 5a9896706c
)
Co-authored-by: behzad nouri <behzadnouri@gmail.com>