Update fe-idea-dev.md (#4852)

* Update fe-idea-dev.md

use `brew install thrift@0.9` to install thrift 0.9.3.1
`brew edit thrift090 | head` shows thrift@0.9 uses thrift 0.9.3.1

* [Refactor] Remove the unnecessary if statement

Future<?> submit(Runnable task)
Submits a Runnable task for execution and returns a Future representing that task. The Future's get method will return null upon successful completion.

docs/zh-CN/developer-guide/fe-idea-dev.md

@@ -38,8 +38,7 @@ JDK1.8+, IntelliJ IDEA
 
     1. 安装 thrift 0.9.3 版本。
 
-        MacOS: `brew install https://gist.githubusercontent.com/chrislusf/8b4e7c19551ba220232f037b43c0eaf3/raw/01465b867b8ef9af7c7c3fa830c83666c825122d/thrift.rb`
-
+        MacOS: `brew install thrift@0.9`
         Windows: `http://archive.apache.org/dist/thrift/0.9.3/thrift-0.9.3.exe`
 
 4. 如果是Mac 或者 Linux 环境 可以通过 如下命令生成自动生成代码：

fe/fe-core/src/main/java/org/apache/doris/qe/ConnectScheduler.java

@@ -89,10 +89,7 @@ public class ConnectScheduler {
         if(context instanceof NConnectContext){
             return true;
         }
-        if (executor.submit(new LoopHandler(context)) == null) {
-            LOG.warn("Submit one thread failed.");
-            return false;
-        }
+        executor.submit(new LoopHandler(context));
         return true;
     }