OAK-11254 : added sleep after creation of DocumentNodeStore to reduce…

… likelyhood of backgroundPurge to interfere with testing and clean up branch commits on root

oak-store-document/src/test/java/org/apache/jackrabbit/oak/plugins/document/BranchCommitGCTest.java

@@ -759,7 +759,15 @@ private DocumentNodeStore newStore(int clusterId) {
         if (clusterId > 0) {
             builder.setClusterId(clusterId);
         }
-        return builder.getNodeStore();
+        DocumentNodeStore nodeStore = builder.getNodeStore();
+        // OAK-11254 : adding a temporary sleep to reduce likelyhood of
+        // backgroundPurge to interfere with test
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            fail("got interrupted");
+        }
+        return nodeStore;
     }
 
     private RevisionVector mergedBranchCommit(Consumer<NodeBuilder> buildFunction) throws Exception {