Only mark block lookups as pending if block is importing from gossip (#8112)

- PR https://github.com/sigp/lighthouse/pull/8045 introduced a regression of how lookup sync interacts with the da_checker.

Now in unstable block import from the HTTP API also insert the block in the da_checker while the block is being execution verified. If lookup sync finds the block in the da_checker in `NotValidated` state it expects a `GossipBlockProcessResult` message sometime later. That message is only sent after block import in gossip.

I confirmed in our node's logs for 4/4 cases of stuck lookups are caused by this sequence of events:
- Receive block through API, insert into da_checker in fn process_block in put_pre_execution_block
- Create lookup and leave in AwaitingDownload(block in processing cache) state
- Block from HTTP API finishes importing
- Lookup is left stuck

Closes https://github.com/sigp/lighthouse/issues/8104


  - https://github.com/sigp/lighthouse/pull/8110 was my initial solution attempt but we can't send the `GossipBlockProcessResult` event from the `http_api` crate without adding new channels, which seems messy.

For a given node it's rare that a lookup is created at the same time that a block is being published. This PR solves https://github.com/sigp/lighthouse/issues/8104 by allowing lookup sync to import the block twice in that case.


Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>

beacon_node/beacon_chain/src/data_availability_checker.rs

@@ -21,8 +21,8 @@ use task_executor::TaskExecutor;
 use tracing::{debug, error, instrument};
 use types::blob_sidecar::{BlobIdentifier, BlobSidecar, FixedBlobSidecarList};
 use types::{
-    BlobSidecarList, ChainSpec, DataColumnSidecar, DataColumnSidecarList, Epoch, EthSpec, Hash256,
-    SignedBeaconBlock, Slot,
+    BlobSidecarList, BlockImportSource, ChainSpec, DataColumnSidecar, DataColumnSidecarList, Epoch,
+    EthSpec, Hash256, SignedBeaconBlock, Slot,
 };
 
 mod error;
@@ -354,9 +354,10 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
         &self,
         block_root: Hash256,
         block: Arc<SignedBeaconBlock<T::EthSpec>>,
+        source: BlockImportSource,
     ) -> Result<(), Error> {
         self.availability_cache
-            .put_pre_execution_block(block_root, block)
+            .put_pre_execution_block(block_root, block, source)
     }
 
     /// Removes a pre-execution block from the cache.