synapse_auto_compressor panics on start after using the history delete api to remove remote events

Describe the bug

Nov 25 00:25:08 nordgedanken.dev systemd[1]: Starting State Compress Synapse...
Nov 25 00:25:08 nordgedanken.dev synapse_auto_compressor[3600348]: [2021-11-24T23:25:08Z INFO  synapse_auto_compressor] synapse_auto_compressor started
Nov 25 00:25:08 nordgedanken.dev synapse_auto_compressor[3600348]: [2021-11-24T23:25:08Z INFO  synapse_auto_compressor::manager] Running compressor on room !OGEhHVWSdvArJzumhm:matrix.org with chunk size 1000
Nov 25 00:25:10 nordgedanken.dev synapse_auto_compressor[3600348]: [2021-11-24T23:25:10Z ERROR panic] thread 'main' panicked at 'Missing 13719240': src/lib.rs:666
Nov 25 00:25:10 nordgedanken.dev systemd[1]: synapse-state-compress.service: Main process exited, code=exited, status=101/n/a
Nov 25 00:25:10 nordgedanken.dev systemd[1]: synapse-state-compress.service: Failed with result 'exit-code'.
Nov 25 00:25:10 nordgedanken.dev systemd[1]: Failed to start State Compress Synapse.

To Reproduce
Steps to reproduce the behavior:

1. Run purge_history on a room
2. start synapse_auto_compressor

Expected behavior
It runs or atleast ignores the invalid rooms

Start by reproducing the failure with purge_history, then inspect the panic at src/lib.rs:666 and the synapse_auto_compressor startup path. Trace how rooms and remote events are looked up after history deletion; done means the compressor runs successfully or ignores invalid rooms without panicking.