DDN-941 test: relax sanity 450 memory checking

DDN-941 test: relax sanity 450 memory checking

For debugging purpose, it could be helpful to output
memory usage.

Memory checking somehow not working, before figuring it
out, let's only output it rather than error to make
we don't block other patches landing.

Test-Parameters: trivial
Change-Id: I76dcac18824f2fe3b2f8d1a86abe3fd6cba40a3e
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-on: https://review.whamcloud.com/41836
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>