Make max_blobs_per_block a config parameter (#6329)

* First pass

* Add restrictions to RuntimeVariableList api

* Use empty_uninitialized and fix warnings

* Fix some todos

* Merge branch 'unstable' into max-blobs-preset

* Fix take impl on RuntimeFixedList

* cleanup

* Fix test compilations

* Fix some more tests

* Fix test from unstable

* Merge branch 'unstable' into max-blobs-preset

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

* Remove footgun function

* Minor simplifications

* Move from preset to config

* Fix typo

* Revert "Remove footgun function"

This reverts commit de01f923c7.

* Try fixing tests

* Thread through ChainSpec

* Fix release tests

* Move RuntimeFixedVector into module and rename

* Add test

* Remove empty RuntimeVarList awefullness

* Fix tests

* Simplify BlobSidecarListFromRoot

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

* Bump quota to account for new target (6)

* Remove clone

* Fix issue from review

* Try to remove ugliness

* Merge branch 'unstable' into max-blobs-preset

* Fix max value

* Fix doctest

* Fix formatting

* Fix max check

* Delete hardcoded max_blobs_per_block in RPC limits

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

beacon_node/beacon_chain/src/fetch_blobs.rs

@@ -21,8 +21,8 @@ use std::sync::Arc;
 use tokio::sync::mpsc::Receiver;
 use types::blob_sidecar::{BlobSidecarError, FixedBlobSidecarList};
 use types::{
-    BeaconStateError, BlobSidecar, DataColumnSidecar, DataColumnSidecarList, EthSpec, FullPayload,
-    Hash256, SignedBeaconBlock, SignedBeaconBlockHeader,
+    BeaconStateError, BlobSidecar, ChainSpec, DataColumnSidecar, DataColumnSidecarList, EthSpec,
+    FullPayload, Hash256, SignedBeaconBlock, SignedBeaconBlockHeader,
 };
 
 pub enum BlobsOrDataColumns<T: BeaconChainTypes> {
@@ -112,6 +112,7 @@ pub async fn fetch_and_process_engine_blobs<T: BeaconChainTypes>(
         response,
         signed_block_header,
         &kzg_commitments_proof,
+        &chain.spec,
     )?;
 
     let num_fetched_blobs = fixed_blob_sidecar_list
@@ -275,8 +276,11 @@ fn build_blob_sidecars<E: EthSpec>(
     response: Vec<Option<BlobAndProofV1<E>>>,
     signed_block_header: SignedBeaconBlockHeader,
     kzg_commitments_inclusion_proof: &FixedVector<Hash256, E::KzgCommitmentsInclusionProofDepth>,
+    spec: &ChainSpec,
 ) -> Result<FixedBlobSidecarList<E>, FetchEngineBlobError> {
-    let mut fixed_blob_sidecar_list = FixedBlobSidecarList::default();
+    let epoch = block.epoch();
+    let mut fixed_blob_sidecar_list =
+        FixedBlobSidecarList::default(spec.max_blobs_per_block(epoch) as usize);
     for (index, blob_and_proof) in response
         .into_iter()
         .enumerate()