Always use committee index 0 when getting attestation data

[chong-he]

Issue Addressed

• Validator client does not ask for committee index 0 on attestation data request #8046

Proposed Changes

Split the function publish_attestations_and_aggregates into publish_attestations and handle_aggregates, so that for attestations, only 1 task is spawned.

Additional Info

Tested with Kurtosis on minimal preset, which has a max_committees_per_slot of 4. The number of times the VC calls the BN for the endpoint /eth/v1/validator/attestation_data is given by the metric: http_api_paths_times_count{path="v1/validator/attestation_data"}

For 100 slots of data:
Before: http_api_paths_times_count{path="v1/validator/attestation_data"} 398
After: http_api_paths_times_count{path="v1/validator/attestation_data"} 100

From the test output, we see that the number of calls to the BN is reduced. On mainnet, the max_committee_per_slot is 64, the VC should only call the BN only once per slot for this endpoint

[michaelsproul]

Could use spawn_handle and then await the handle to get the attestation data from inside the future (rather than using the attestation_data_cache RwLock).

[michaelsproul]

In case the handle doesn't return the result, it's an error and we probably need to just stop the attestation process for this slot (return Err(..))

[chong-he]

Thank you for the comment, I revised in 0967696

[michaelsproul]

Could keep these logs (these won't be 0, because the duty still contains the real committee index).

[chong-he]

Good point, revised in 0967696

[michaelsproul]

This drop probably not needed (can just rename the timer to _attestations_timer and it will drop when it goes out of scope, when the function finishes)

[chong-he]

Put a underscore before the timer and removed this line: 0967696

[mergify]

Some required checks have failed. Could you please take a look @chong-he? 🙏