AbstractElasticIndex: Don't mention "change" in exception message

This abstract class is used for all index types. Mentioning "change"
in the error message will cause confusion.

Change-Id: I3260228121a0208945ef6a14357d6c47f5345828

gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java

diff --git a/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java b/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
index 2bad0cb..3d38d13 100644
--- a/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
+++ b/gerrit-elasticsearch/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
@@ -151,7 +151,7 @@
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(
-          String.format("Failed to delete change %s in index %s: %s", c, indexName, statusCode));
+          String.format("Failed to delete %s from index %s: %s", c, indexName, statusCode));
     }
   }