IndexType: Make elasticsearch candidate check consistent w/ constructor

By means of also converting the passed type candidate to lowercase,
before doing the said check.

Change-Id: I99867c4f2b1590b965a9f692e795b02b0d19be1c

java/com/google/gerrit/index/IndexType.java

@@ -58,7 +58,7 @@ public class IndexType {
   }
 
   public static boolean isElasticsearch(String type) {
-    return type.equals(ELASTICSEARCH);
+    return type.toLowerCase().equals(ELASTICSEARCH);
   }
 
   @Override