## Issue Addressed
*Should* address #1917
## Proposed Changes
Stops the `BackgroupMigrator` rx channel from backing up with big `BeaconState` messages.
Looking at some logs from my Medalla node, we can see a discrepancy between the head finalized epoch and the migrator finalized epoch:
```
Nov 17 16:50:21.606 DEBG Head beacon block slot: 129214, root: 0xbc7a…0b99, finalized_epoch: 4033, finalized_root: 0xf930…6562, justified_epoch: 4035, justified_root: 0x206b…9321, service: beacon
Nov 17 16:50:21.626 DEBG Batch processed service: sync, processed_blocks: 43, last_block_slot: 129214, chain: 8274002112260436595, first_block_slot: 129153, batch_epoch: 4036
Nov 17 16:50:21.626 DEBG Chain advanced processing_target: 4036, new_start: 4036, previous_start: 4034, chain: 8274002112260436595, service: sync
Nov 17 16:50:22.162 DEBG Completed batch received awaiting_batches: 5, blocks: 47, epoch: 4048, chain: 8274002112260436595, service: sync
Nov 17 16:50:22.162 DEBG Requesting batch start_slot: 129601, end_slot: 129664, downloaded: 0, processed: 0, state: Downloading(16Uiu2HAmG3C3t1McaseReECjAF694tjVVjkDoneZEbxNhWm1nZaT, 0 blocks, 1273), epoch: 4050, chain: 8274002112260436595, service: sync
Nov 17 16:50:22.654 DEBG Database compaction complete service: beacon
Nov 17 16:50:22.655 INFO Starting database pruning new_finalized_epoch: 2193, old_finalized_epoch: 2192, service: beacon
```
I believe this indicates that the migrator rx has a backed-up queue of `MigrationNotification` items which each contain a `BeaconState`.
## TODO
- [x] Remove finalized state requirement for op-pool
103103e72e