Fix Flogger issues flagged by error prone

Change-Id: Ifbf514ba38bbcbb934e4a4f64865c0a858653679
diff --git a/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java b/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
index d4f2c5d..fce86b9 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
@@ -436,7 +436,7 @@
             };
           }
         } else {
-          logger.atSevere().log(statusLine.getReasonPhrase());
+          logger.atSevere().log("%s", statusLine.getReasonPhrase());
         }
         return new ListResultSet<>(ImmutableList.of());
       } catch (IOException e) {
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticIndexVersionDiscovery.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticIndexVersionDiscovery.java
index 100022a..4217f45 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticIndexVersionDiscovery.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticIndexVersionDiscovery.java
@@ -49,7 +49,7 @@
           String.format(
               "Failed to discover index versions for %s: %d: %s",
               name, statusLine.getStatusCode(), statusLine.getReasonPhrase());
-      logger.atSevere().log(message);
+      logger.atSevere().log("%s", message);
       throw new IOException(message);
     }