Always open files with configured block size

If the Avro file already exists, it should be opened with the configured
block size instead of the default block size of 16 kilobytes.

server/modules/routing/avro/avro_file.c

@@ -122,7 +122,7 @@ AVRO_TABLE* avro_table_alloc(const char* filepath, const char* json_schema, size
 
         if (access(filepath, F_OK) == 0)
         {
-            rc = avro_file_writer_open(filepath, &table->avro_file);
+            rc = avro_file_writer_open_bs(filepath, &table->avro_file, block_size);
         }
         else
         {