[SPARK-28302][CORE] Make sure to generate unique output file for SparkLauncher on Windows

## What changes were proposed in this pull request?

When using SparkLauncher to submit applications **concurrently** with multiple threads under **Windows**, some apps would show that "The process cannot access the file because it is being used by another process" and remains in LOST state at the end. The issue can be reproduced by  this [demo](https://issues.apache.org/jira/secure/attachment/12973920/Main.scala).

After digging into the code, I find that, Windows cmd `%RANDOM%` would return the same number if we call it  instantly(e.g. < 500ms) after last call. As a result, SparkLauncher would get same output file(spark-class-launcher-output-%RANDOM%.txt) for apps. Then, the following app would hit the issue when it tries to write the same file which has already been opened for writing by another app.

We should make sure to generate unique output file for SparkLauncher on Windows to avoid this issue.

## How was this patch tested?

Tested manually on Windows.

Closes apache#25076 from Ngone51/SPARK-28302.

Authored-by: wuyi <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: Ngone51

bin/spark-class2.cmd

@@ -63,7 +63,12 @@ if not "x%JAVA_HOME%"=="x" (
 
 rem The launcher library prints the command to be executed in a single line suitable for being
 rem executed by the batch interpreter. So read all the output of the launcher into a variable.
+:gen
 set LAUNCHER_OUTPUT=%temp%\spark-class-launcher-output-%RANDOM%.txt
+rem SPARK-28302: %RANDOM% would return the same number if we call it instantly after last call,
+rem so we should make it sure to generate unique file to avoid process collision of writing into
+rem the same file concurrently.
+if exist %LAUNCHER_OUTPUT% goto :gen
 "%RUNNER%" -Xmx128m -cp "%LAUNCH_CLASSPATH%" org.apache.spark.launcher.Main %* > %LAUNCHER_OUTPUT%
 for /f "tokens=*" %%i in (%LAUNCHER_OUTPUT%) do (
   set SPARK_CMD=%%i