Enable and fix Eclipse warnings about redundant type arguments

Since Java 7 it is possible to replace the type arguments required to
invoke the constructor of a generic class with an empty set of type
parameters (<>) as long as the compiler can infer the type arguments
from the context [1].

Enable the Eclipse warning about redundant type arguments, and remove
the ones it warns about.

[1] http://goo.gl/SG21kM

Change-Id: I422882949a6a6a57391580d881f73120b2843a0e

gerrit-lucene/src/main/java/com/google/gerrit/lucene/SubIndex.java

@@ -108,7 +108,7 @@ class SubIndex {
 
     notDoneNrtFutures = Sets.newConcurrentHashSet();
 
-    reopenThread = new ControlledRealTimeReopenThread<IndexSearcher>(
+    reopenThread = new ControlledRealTimeReopenThread<>(
         writer, searcherManager,
         0.500 /* maximum stale age (seconds) */,
         0.010 /* minimum stale age (seconds) */);