Fix log redirection under tomcat

The log redirection mechanism loses level for some logs. This is visible when clicking on "add tag" from a document summary page: the DebugUtil method will be called whatever restriction on theses logs is done in the lib/log4j.xml file.
When commenting out the redirection, the logs are not shown, as expected.

This also explains logs like:
ERROR [org.nuxeo.ecm.platform.ui.web.binding.MetaValueExpression] Error processing method expression #

{noteActions.translateImageLinks(field_0)}

: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'noteActions' resolved to null