EX-6931 tests: add version check in sanity test_904

EX-6931 tests: add version check in sanity test_904

The patch that added hide virtual projid xattr functionality
to b_es6_0 branch was submitted under a tag of 2.14.0-ddn55.
In case of interop testing with older servers test 904 fails.
At the same time the rest of the test should still run on
older servers, so I moved parts of the code related to hide
virtual projid xattr functionality under version check
condition.

Sanity test 904 was modified.

Fixes: 8acf413647 ("LU-15548 osd-ldiskfs: hide virtual projid xattr")
Test-Parameters: trivial testlist=sanity env=ONLY="904"
Test-Parameters: testlist=sanity env=ONLY="904" serverversion=2.14.0-ddn54
Signed-off-by: Alena Nikitenko <anikitenko@ddn.com>
Change-Id: Ie3bc67cb8a7a83954f3b2048f009f84ab77bf53d
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51484
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>