LU-17305 obdclass: do not link all exports to obd's timed list

LU-17305 obdclass: do not link all exports to obd's timed list

Osp device may get class_cleanup()-ed in course of evictor process
where obd->u.cli.cl_import gets zeroed:
ping_evictor_main
  class_fail_export
    obd_disconnect
      osp_obd_disconnect
        class_manual_cleanup
          class_process_config(LCFG_CLEANUP)
            class_cleanup
              obd_precleanup
                osp_device_fini
                  client_obd_cleanup
                    obd_cleanup_client_import
                      obd->u.cli.cl_import = NULL;

osp-pre threads are not stopped by the evictor, which leads to
assertion on:
osp_precreate_thread
  osp_statfs_update
    imp = d->opd_obd->u.cli.cl_import;
    LASSERT(imp);

Test to illustrate the issue is added.

Add to obd's timed list only evictable exports

HPE-bug-id: LUS-11933
Signed-off-by: Vladimir Saveliev <vladimir.saveliev@hpe.com>
Change-Id: I1aab4a573fc4ef33d53d822bec1a28dd3bcece74
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53192
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Vitaly Fertman <vitaly.fertman@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>