Do not add passengers of entities that were above save limit (#5073)

Co-authored-by: Spottedleaf <spottedleaf@spottedleaf.dev>

Spigot-Server-Patches/Entity-load-save-limit-per-chunk.patch

@@ -80,7 +80,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +                final int saveLimit = world.paperConfig.entityPerChunkSaveLimits.getOrDefault(entityType, -1);
 +                if (saveLimit > -1) {
 +                    if (loadedEntityCounts.getOrDefault(entityType, 0) >= saveLimit) {
-+                        return entity;
++                        return null;
 +                    }
 +                    loadedEntityCounts.merge(entityType, 1, Integer::sum);
 +                }