[ZEPPELIN-5052]. Unable to set multiple local properties in ZSession

### What is this PR for?

The root cause is that the local properties format is not correct, we should separate them via dot.  This PR fix it and also add unit test for this scenario.

### What type of PR is it?
[Bug Fix ]

### Todos
* [ ] - Task

### What is the Jira issue?
* https://issues.apache.org/jira/browse/ZEPPELIN-5052

### How should this be tested?
* CI pass

### Screenshots (if appropriate)

### Questions:
* Does the licenses files need update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? No

Author: Jeff Zhang <[email protected]>

Closes apache#3916 from zjffdu/ZEPPELIN-5052 and squashes the following commits:

08229d9 [Jeff Zhang] [ZEPPELIN-5052]. Unable to set multiple local properties in ZSession

zeppelin-client/src/main/java/org/apache/zeppelin/client/ZSession.java

@@ -27,7 +27,9 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 /**
  * Each ZSession represent one interpreter process, you can start/stop it, and execute/submit/cancel code.
@@ -263,9 +265,10 @@ public ExecuteResult execute(String subInterpreter,
     }
     if (localProperties != null && !localProperties.isEmpty()) {
       builder.append("(");
-      for (Map.Entry<String, String> entry : localProperties.entrySet()) {
-        builder.append(entry.getKey() + "=\"" + entry.getValue() + "\"");
-      }
+      List<String> propertyString = localProperties.entrySet().stream()
+              .map(entry -> (entry.getKey() + "=\"" + entry.getValue() + "\""))
+              .collect(Collectors.toList());
+      builder.append(StringUtils.join(propertyString, ","));
       builder.append(")");
     }
     builder.append("\n" + code);

zeppelin-interpreter-integration/src/test/java/org/apache/zeppelin/integration/ZSessionIntegrationTest.java

@@ -324,6 +324,7 @@ public void testZSession_Flink() throws Exception {
       assertEquals(result.toString(), Status.FINISHED, result.getStatus());
       Map<String, String> localProperties = new HashMap<>();
       localProperties.put("type", "update");
+      localProperties.put("parallelism", "2");
       result = session.execute("ssql", localProperties, "select url, count(1) as pv from log group by url");
       assertEquals(result.toString(), Status.FINISHED, result.getStatus());