Move plugin underneath 'its' package hierarchy This plugin was called 'hooks-bugzilla' before, which lived underneath '[...].plugins.hooks.bz'. Some time ago, the repository got renamed to 'its-bugzilla', but the package name has not yet been updated. Hence we update it now to match the package of its-phabricator and its-storyboard. Change-Id: I941589b6acc36a89a1d835cff4e0a5008f7c928f