LU-10562 tests: fix non-portable bash redirection

LU-10562 tests: fix non-portable bash redirection

Replace non-portable bash redirection with a simple(r) array
assignment.  This was reporting for at least bash 4.4.26:

   line 5211: syntax error near unexpected token `<'

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I8289a4a3a1518c3cb6f33e2d8e52ba22db3ebbe5
Reviewed-on: https://review.whamcloud.com/31050
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Cliff White <cliff.white@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>