beacon-chain/das: remove dead slot parameter (#16021)

The slot parameter in blobCacheEntry.filter was unused and redundant.
All slot/epoch-sensitive checks happen before filter
(commitmentsToCheck), and disk availability is handled via
BlobStorageSummary (epoch-aware).

Changes:
- Drop slot from blobCacheEntry.filter signature.
- Update call sites in availability_blobs.go and blob_cache_test.go.

Mirrors the data_column_cache.filter API (which does not take slot),
reduces API noise, and removes dead code without changing behavior.

beacon-chain/das/availability_blobs.go

@@ -100,7 +100,7 @@ func (s *LazilyPersistentStoreBlob) IsDataAvailable(ctx context.Context, current
 	// Verify we have all the expected sidecars, and fail fast if any are missing or inconsistent.
 	// We don't try to salvage problematic batches because this indicates a misbehaving peer and we'd rather
 	// ignore their response and decrease their peer score.
-	sidecars, err := entry.filter(root, blockCommitments, b.Block().Slot())
+	sidecars, err := entry.filter(root, blockCommitments)
 	if err != nil {
 		return errors.Wrap(err, "incomplete BlobSidecar batch")
 	}