ElasticContainer: Include cause in AssumptionViolatedException

Providing the cause will make failure logs more useful.

Change-Id: I08e0688fd7cb5c8e367aa6cb5c987397b693d207
diff --git a/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/testing/ElasticContainer.java b/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/testing/ElasticContainer.java
index 56b83be..c87ab9d 100644
--- a/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/testing/ElasticContainer.java
+++ b/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/testing/ElasticContainer.java
@@ -34,7 +34,7 @@
       container.start();
       return container;
     } catch (Throwable t) {
-      throw new AssumptionViolatedException("Unable to start container[might be docker related]");
+      throw new AssumptionViolatedException("Unable to start container", t);
     }
   }