[findbugs] Avoid futile attempt to change max pool size

Javadoc for ScheduledThreadPoolExecutor says [1]:
While ScheduledThreadPoolExecutor inherits from ThreadPoolExecutor, a
few of the inherited tuning methods are not useful for it. In
particular, because it acts as a fixed-sized pool using corePoolSize
threads and an unbounded queue, adjustments to maximumPoolSize have no
useful effect. 

[1]
http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ScheduledThreadPoolExecutor.html

Change-Id: I8eccb7d6544aa6e27f5fa064c19dddb2a706523f
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchingProgressMonitor.java

@@ -74,7 +74,6 @@ public abstract class BatchingProgressMonitor implements ProgressMonitor {
 						return thr;
 					}
 				});
-		alarmQueue.setMaximumPoolSize(alarmQueue.getCorePoolSize());
 		alarmQueue.setContinueExistingPeriodicTasksAfterShutdownPolicy(false);
 		alarmQueue.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
 		alarmQueue.prestartAllCoreThreads();