HBASE-26468 Region Server doesn't exit cleanly incase it crashes.

Author: shahrs87

hbase-server/src/main/java/org/apache/hadoop/hbase/util/ServerCommandLine.java

@@ -141,15 +141,13 @@ public static void logProcessInfo(Configuration conf) {
   }
 
   /**
-   * Parse and run the given command line. This may exit the JVM if
-   * a nonzero exit code is returned from <code>run()</code>.
+   * Parse and run the given command line. This will exit the JVM with
+   * the exit code returned from <code>run()</code>.
    */
   public void doMain(String args[]) {
     try {
       int ret = ToolRunner.run(HBaseConfiguration.create(), this, args);
-      if (ret != 0) {
-        System.exit(ret);
-      }
+      System.exit(ret);
     } catch (Exception e) {
       LOG.error("Failed to run", e);
       System.exit(-1);