EX-9125 tests: change source dir for sanity-compr/1008

EX-9125 tests: change source dir for sanity-compr/1008

While the source directory contains almost all small files,
sanity-compr test_1008 will hit the
"failed estimates > 50% of total estimates" failure on SLES15.

The patch fixes the issue by changing the source dir to
contain large files.

Test-Parameters: trivial clientdistro=sles15sp5 \
  testlist=sanity-compr env=ONLY="1008",ONLY_REPEAT=3

Test-Parameters: trivial clientdistro=el9.3 \
  testlist=sanity-compr env=ONLY="1008",ONLY_REPEAT=3

Test-Parameters: trivial clientdistro=el8.8 \
  testlist=sanity-compr env=ONLY="1008",ONLY_REPEAT=3

Change-Id: Iad661750cba7c9d2204f2306e73169deb012ddf4
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/55334
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>