YARN-8791. Trim docker inspect output for line feed for STOPSIGNAL parsing.

           Contributed by Chandni Singh

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/runtime/DockerLinuxContainerRuntime.java

@@ -1282,7 +1282,7 @@ public class DockerLinuxContainerRuntime implements LinuxContainerRuntime {
             DockerInspectCommand.STATUS_TEMPLATE,
             DockerInspectCommand.STOPSIGNAL_TEMPLATE}, delimiter);
     try {
-      String output = executeDockerInspect(containerId, inspectCommand);
+      String output = executeDockerInspect(containerId, inspectCommand).trim();
 
       if (!output.isEmpty()) {
         String[] statusAndSignal = StringUtils.split(output, delimiter);