MultiProgressMonitor#waitFor: Fix Javadoc of thrown exception

In change I6a4b2731f the waitFor method was changed to throw
TimeoutException instead of ExecutionException, but the Javadoc
was not updated.

Change-Id: Iefa7692efb81e4087542cea9918ae82651f45f7b
diff --git a/java/com/google/gerrit/server/git/MultiProgressMonitor.java b/java/com/google/gerrit/server/git/MultiProgressMonitor.java
index 7b976e8..2d854a5 100644
--- a/java/com/google/gerrit/server/git/MultiProgressMonitor.java
+++ b/java/com/google/gerrit/server/git/MultiProgressMonitor.java
@@ -184,7 +184,7 @@
    * @param timeoutTime overall timeout for the task; the future is forcefully cancelled if the task
    *     exceeds the timeout. Non-positive values indicate no timeout.
    * @param timeoutUnit unit for overall task timeout.
-   * @throws ExecutionException if this thread or a worker thread was interrupted, the worker was
+   * @throws TimeoutException if this thread or a worker thread was interrupted, the worker was
    *     cancelled, or timed out waiting for a worker to call {@link #end()}.
    */
   public <T> T waitFor(Future<T> workerFuture, long timeoutTime, TimeUnit timeoutUnit)