Remove job added as part of WKINIT-4 and rely on listener priority instead

Thomas Mortagne pointed rightfully in WKINIT-4 that it's now possible to prioritize event listeners by default with the @Priority annotation. The fuss with adding a 5 second delay at startup is then not needed anymore (https://jira.xwiki.org/browse/WKINIT-4?focusedId=118278&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-118278).