tests: don't run sed multiple times on test output

tests: don't run sed multiple times on test output

Don't call sed multiple times on the output, and avoid the use
of temporary files, or if possible.  It would be convenient to
use "sed -i" to only update the output file once, but this is
not portable to all platforms.

[ Fixed a few test regression failures --tytso ]

Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>