tests: write f_badjour_encrypted output to log

tests: write f_badjour_encrypted output to log

Write the mke2fs and debugfs output from f_badjour_encrypted/script
into a log file instead of stdout/stderr, so that it doesn't mess
up the "make check" output, and is available if this test ever fails.

   [ Fixed missing definition of $LOG -- TYT ]

Fixes: b0cd09e5 ("e2fsck: don't allow journal to have encrypt flag")
Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20240605200408.55221-1-adilger@dilger.ca
Signed-off-by: Theodore Ts'o <tytso@mit.edu>