LU-10695 tests: fix sanity-lfsck test_23c

LU-10695 tests: fix sanity-lfsck test_23c

sanity-lfsck test_23c fails intermittently with "(8) unexpected size"
while introducing the required corruption to the filesystem to run
the test.

It appears that in these cases, LFSCK has actually fixed the file
before it can be "further corrupted" as part of the test.  In
this case, the test failure is actually a sign that LFSCK is working
correctly, so it should not be considered a test failure.

Add a check that the file was repaired correctly (contains original
data) and consider the test a pass.

Test-Parameters: trivial testlist=sanity-lfsck,sanity-lfsck,sanity-lfsck mdtfilesystemtype=zfs ostfilesystemtype=zfs
Test-Parameters: testlist=sanity-lfsck,sanity-lfsck,sanity-lfsck mdtfilesystemtype=zfs ostfilesystemtype=zfs
Test-Parameters: testlist=sanity-lfsck,sanity-lfsck,sanity-lfsck mdtfilesystemtype=zfs ostfilesystemtype=zfs
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I9d92cd8e471426cc544293e1149ad556a33ebbe5
Reviewed-on: https://review.whamcloud.com/33407
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>