HADOOP-15876. Use keySet().removeAll() to remove multiple keys from Map in AzureBlobFileSystemStore

Contributed by Da Zhou.

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AzureBlobFileSystemStore.java

@@ -678,9 +678,7 @@ public class AzureBlobFileSystemStore {
       }
     }
 
-    for (Map.Entry<String, String> defaultAclEntry : defaultAclEntries.entrySet()) {
-      aclEntries.remove(defaultAclEntry.getKey());
-    }
+    aclEntries.keySet().removeAll(defaultAclEntries.keySet());
 
     client.setAcl(AbfsHttpConstants.FORWARD_SLASH + getRelativePath(path, true),
         AbfsAclHelper.serializeAclSpec(aclEntries), eTag);