Dora is unhappy with lodestar SSE events

Reported by Barnabas
> also there seems to be some sse handler bugs that cause dora to freak out from lodestar
While poking around I also found that all 5 Lodestar nodes on devnet-5 (both lodestar-ethrex-, both lodestar-nethermind-, lodestar-erigon-1) have a hung
/eth/v1/events SSE handler — Lodestar accepts the request and never writes a response byte, so nginx 504s after 60s. Reproduces directly against
http://127.0.0.1:5052/eth/v1/events?topics=head on the host (bypassing nginx), all topics, with non-SSE endpoints on the same port responding in 1-2ms. Image is
ethpandaops/lodestar:glamsterdam-devnet-5 (ce50288, v1.43.0). It's what's been spamming dora warnings — probably what you were debugging.

needs further investigation