Execution layer CRITs in syncing simulator

[michaelsproul]

Description

I noticed some CRIT logs in the syncing simulator that look like they should probably be fixed:

2023-04-14T06:29:30.0233141Z Apr 14 06:29:30.022 CRIT Failed to update execution head error: ExecutionLayerMissing, service: beacon, service: boot_node
2023-04-14T06:29:30.0234096Z Apr 14 06:29:30.022 CRIT Failed to prepare proposers after fork choice, error: ExecutionLayerMissing, service: beacon, service: boot_node

It also seems to struggle to produce blocks:

2023-04-14T06:29:31.0151635Z Apr 14 06:29:31.014 CRIT Error whilst producing block message: Recoverable("Some endpoints failed, num_failed: 3 http://127.0.0.1:42423/ => Unavailable(Offline), http://127.0.0.1:33663/ => RequestFailed(Recoverable("Error from beacon node when producing block: ServerMessage(ErrorMessage { code: 500, message: \"UNHANDLED_ERROR: ExecutionLayerMissing\", stacktraces: [] })")), http://127.0.0.1:42423/ => Unavailable(Offline)"), service: block, service: validator_0

Logs: https://pipelines.actions.githubusercontent.com/serviceHosts/8f3ef1b0-5259-4ede-9a2c-4c3c49841572/_apis/pipelines/1/runs/22582/signedlogcontent/65?urlExpires=2023-04-14T06%3A35%3A10.6485036Z&urlSigningMethod=HMACV1&urlSignature=JoPPE4uLD8SMJ0Ycb5pekwfkNkjwEkuF3yf2hzeT56A%3D