EX-7795 tests: add sanity-compr test for compression

EX-7795 tests: add sanity-compr test for compression

This patch adds a sanity-compr test to validate that
we get space usage reduction with compression.
The test uses ll_compression_scan tool to calculate
the compressed size of the source file and compares
it with the size of the Lustre CSDC compressed file.

Test-Parameters: trivial env=ONLY=1007 testlist=sanity-compr

Change-Id: Icf763331205a3e937b794f90444f756fc59f9050
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52895
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sarah Liu <sarah@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>