fixed that "async" parallelism must be power of two - so don't use "m…

…axBulkSize" for that

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

thingsearch/service/src/main/java/org/eclipse/ditto/thingsearch/service/persistence/write/streaming/MongoSearchUpdaterFlow.java

@@ -114,7 +114,7 @@ public Flow<SubSource<AbstractWriteModel, NotUsed>, WriteResultAndErrors, NotUse
                         .flatMapConcat(searchUpdateMapper::processWriteModels)
                         .flatMapMerge(parallelism, writeModels -> executeBulkWrite(shouldAcknowledge, writeModels))
                         .mergeSubstreamsWithParallelism(maxBulkSize)
-                        .async(MongoSearchUpdaterFlow.DISPATCHER_NAME, Math.max(parallelism, maxBulkSize))
+                        .async(MongoSearchUpdaterFlow.DISPATCHER_NAME, parallelism)
                 );
     }