[SPARK-3900] ApplicationMaster's shutdown hook fails and IllegalStateException is thrown.

ApplicationMaster registers a shutdown hook and it calls ApplicationMaster#cleanupStagingDir.

cleanupStagingDir invokes FileSystem.get(yarnConf) and it invokes FileSystem.getInternal. FileSystem.getInternal also registers shutdown hook.
In FileSystem of hadoop 0.23, the shutdown hook registration does not consider whether shutdown is in progress or not (In 2.2, it's considered).

    // 0.23 
    if (map.isEmpty() ) {
      ShutdownHookManager.get().addShutdownHook(clientFinalizer, SHUTDOWN_HOOK_PRIORITY);
    }

    // 2.2
    if (map.isEmpty()
                && !ShutdownHookManager.get().isShutdownInProgress()) {
       ShutdownHookManager.get().addShutdownHook(clientFinalizer, SHUTDOWN_HOOK_PRIORITY);
    }

Thus, in 0.23, another shutdown hook can be registered when ApplicationMaster's shutdown hook run.

This issue cause IllegalStateException as follows.

    java.lang.IllegalStateException: Shutdown in progress, cannot add a shutdownHook
            at org.apache.hadoop.util.ShutdownHookManager.addShutdownHook(ShutdownHookManager.java:152)
            at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2306)
            at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2278)
            at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:316)
            at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:162)
            at org.apache.spark.deploy.yarn.ApplicationMaster.org$apache$spark$deploy$yarn$ApplicationMaster$$cleanupStagingDir(ApplicationMaster.scala:307)
            at org.apache.spark.deploy.yarn.ApplicationMaster$$anon$3.run(ApplicationMaster.scala:118)
            at org.apache.hadoop.util.ShutdownHookManager$1.run(ShutdownHookManager.java:54)