[SPARK-12399] Display correct error message when accessing REST API with an unknown app Id

I got an exception when accessing the below REST API with an unknown application Id.
`http://<server-url>:18080/api/v1/applications/xxx/jobs`
Instead of an exception, I expect an error message "no such app: xxx" which is a similar error message when I access `/api/v1/applications/xxx`
```
org.spark-project.guava.util.concurrent.UncheckedExecutionException: java.util.NoSuchElementException: no app with key xxx
	at org.spark-project.guava.cache.LocalCache$Segment.get(LocalCache.java:2263)
	at org.spark-project.guava.cache.LocalCache.get(LocalCache.java:4000)
	at org.spark-project.guava.cache.LocalCache.getOrLoad(LocalCache.java:4004)
	at org.spark-project.guava.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4874)
	at org.apache.spark.deploy.history.HistoryServer.getSparkUI(HistoryServer.scala:116)
	at org.apache.spark.status.api.v1.UIRoot$class.withSparkUI(ApiRootResource.scala:226)
	at org.apache.spark.deploy.history.HistoryServer.withSparkUI(HistoryServer.scala:46)
	at org.apache.spark.status.api.v1.ApiRootResource.getJobs(ApiRootResource.scala:66)
```

Author: Carson Wang <carson.wang@intel.com>

Closes #10352 from carsonwang/unknownAppFix.

core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala

@@ -21,6 +21,8 @@ import java.util.NoSuchElementException
 import java.util.zip.ZipOutputStream
 import javax.servlet.http.{HttpServlet, HttpServletRequest, HttpServletResponse}
 
+import scala.util.control.NonFatal
+
 import com.google.common.cache._
 import org.eclipse.jetty.servlet.{ServletContextHandler, ServletHolder}
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
@@ -113,7 +115,17 @@ class HistoryServer(
   }
 
   def getSparkUI(appKey: String): Option[SparkUI] = {
-    Option(appCache.get(appKey))
+    try {
+      val ui = appCache.get(appKey)
+      Some(ui)
+    } catch {
+      case NonFatal(e) => e.getCause() match {
+        case nsee: NoSuchElementException =>
+          None
+
+        case cause: Exception => throw cause
+      }
+    }
   }
 
   initialize()
@@ -193,7 +205,7 @@ class HistoryServer(
       appCache.get(appId + attemptId.map { id => s"/$id" }.getOrElse(""))
       true
     } catch {
-      case e: Exception => e.getCause() match {
+      case NonFatal(e) => e.getCause() match {
         case nsee: NoSuchElementException =>
           false