Use a valid concurrency for a public test

Author: Mats-SX

proc/catalog/src/test/java/org/neo4j/gds/catalog/GraphStreamRelationshipsProcTest.java

@@ -133,7 +133,7 @@ void shouldStreamInParallel() {
         runQuery("CALL gds.beta.graph.generate('generatedGraph', 10000, 5)");
 
         var actualRelationships = new ArrayList<TopologyResult>();
-        runQueryWithRowConsumer("CALL gds.beta.graph.relationships.stream('generatedGraph', ['*'], { concurrency: 10 })", row -> actualRelationships.add(
+        runQueryWithRowConsumer("CALL gds.beta.graph.relationships.stream('generatedGraph', ['*'], { concurrency: 4 })", row -> actualRelationships.add(
             relationship(
                 row.getNumber("sourceNodeId").longValue(),
                 row.getNumber("targetNodeId").longValue(),