Pull repeated computation outside loop in BigQuerySplitManager

Author: findepi

plugin/trino-bigquery/src/main/java/io/trino/plugin/bigquery/BigQuerySplitManager.java

@@ -156,8 +156,9 @@ private List<BigQuerySplit> readFromBigQuery(ConnectorSession session, TableDefi
         }
         ReadSession readSession = createReadSession(session, remoteTableId, ImmutableList.copyOf(projectedColumnsNames), filter, actualParallelism);
 
+        String schemaString = getSchemaAsString(readSession);
         return readSession.getStreamsList().stream()
-                .map(stream -> BigQuerySplit.forStream(stream.getName(), getSchemaAsString(readSession), columns, OptionalInt.of(stream.getSerializedSize())))
+                .map(stream -> BigQuerySplit.forStream(stream.getName(), schemaString, columns, OptionalInt.of(stream.getSerializedSize())))
                 .collect(toImmutableList());
     }