Fix a problem in the DbHandler.run() method that appears to make it possible to
create a tight infinite loop if the method is still running after the database
has been closed, repeatedly catching and logging exceptions.  This change adds
a break statement after logging the message so that it will exit from the loop.

The exception being caught was:

com.sleepycat.je.DatabaseException: (JE 3.2.29) Attempt to use non-open Environment object().
    at com.sleepycat.je.Environment.checkHandleIsValid(Environment.java:1147)
    at com.sleepycat.je.Environment.beginTransactionInternal(Environment.java:731)
    at com.sleepycat.je.Environment.beginTransaction(Environment.java:720)
    at org.opends.server.replication.server.ReplicationDbEnv.beginTransaction(ReplicationDbEnv.java:381)
    at org.opends.server.replication.server.ReplicationDB$ReplServerDBCursor.<init>(ReplicationDB.java:363)
    at org.opends.server.replication.server.ReplicationDB$ReplServerDBCursor.<init>(ReplicationDB.java:314)
    at org.opends.server.replication.server.ReplicationDB.openDeleteCursor(ReplicationDB.java:205)
    at org.opends.server.replication.server.DbHandler.trim(DbHandler.java:384)
    at org.opends.server.replication.server.DbHandler.run(DbHandler.java:335)
    at java.lang.Thread.run(Thread.java:619)