OPENDJ-1929 Code cleanup

* org.opends.guitools.controlpanel.ui.VerifyIndexPanel.java
** Autorefactor'ed file
** Reformat
** Add final keyword
** Remove unecessary javadoc
** Use List instead of ArrayList as declarative type
** Reduce visibility when it was possible
** Extracted method:
*** addNewElements(List<AbstractIndexDescriptor>, String label, List<CategorizedComboBoxElement>)

* org.opends.guitools.controlpanel.ui.RebuildIndexPanel.java
* org.opends.guitools.controlpanel.ui.StatusGenericPanel.java
** Autorefactor'ed file
** Reformat
** Add final keyword
** Remove unecessary javadoc
** Use Set instead of LinkedHashSet as declarative type
** Use Map instead of HashMap as declarative type