generic/095: don't silence fio error output

generic/095: don't silence fio error output

This case print both fio stdout and stderr to .full file, that cause
we miss some unexpected failures when there's a bug. For example:

  file:io_u.c:1803, func=io_u error, error=Block device required

This's an regression issue we find on a downstream kernel, not in
upstream. So release unexpected fio error output to find more issues.

Signed-off-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>