Relax WaitActiveShardCountIT check of exception messages

So ti wouldn't depend on BulkShardRequest.toString()

core/src/test/java/org/elasticsearch/action/support/WaitActiveShardCountIT.java

@@ -33,6 +33,7 @@ import static org.elasticsearch.common.unit.TimeValue.timeValueMillis;
 import static org.elasticsearch.common.unit.TimeValue.timeValueSeconds;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.startsWith;
 
 /**
  * Tests setting the active shard count for replication operations (e.g. index) operates correctly.
@@ -53,7 +54,7 @@ public class WaitActiveShardCountIT extends ESIntegTestCase {
             fail("can't index, does not enough active shard copies");
         } catch (UnavailableShardsException e) {
             assertThat(e.status(), equalTo(RestStatus.SERVICE_UNAVAILABLE));
-            assertThat(e.getMessage(), equalTo("[test][0] Not enough active copies to meet shard count of [2] (have 1, needed 2). Timeout: [100ms], request: [BulkShardRequest to [[test][0]] containing [1] requests]"));
+            assertThat(e.getMessage(), startsWith("[test][0] Not enough active copies to meet shard count of [2] (have 1, needed 2). Timeout: [100ms], request:"));
             // but really, all is well
         }
 
@@ -82,7 +83,7 @@ public class WaitActiveShardCountIT extends ESIntegTestCase {
             fail("can't index, not enough active shard copies");
         } catch (UnavailableShardsException e) {
             assertThat(e.status(), equalTo(RestStatus.SERVICE_UNAVAILABLE));
-            assertThat(e.getMessage(), equalTo("[test][0] Not enough active copies to meet shard count of [" + ActiveShardCount.ALL + "] (have 2, needed 3). Timeout: [100ms], request: [BulkShardRequest to [[test][0]] containing [1] requests]"));
+            assertThat(e.getMessage(), startsWith("[test][0] Not enough active copies to meet shard count of [" + ActiveShardCount.ALL + "] (have 2, needed 3). Timeout: [100ms], request:"));
             // but really, all is well
         }