LU-15542 tests: skip interop conf-sanity test_61b

LU-15542 tests: skip interop conf-sanity test_61b

Skip large_xattr test for old MDS without fix for large_xattr.
Minor cleanup to code style.

Test-Parameters: trivial
Test-Parameters: testlist=conf-sanity env=ONLY="61" serverversion=2.15.0
Fixes: 716de353b7 ("LU-15542 osd-ldiskfs: exclude EA inode from processing")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ieb30568b617177a9986a139b289ba1ced63ebbe5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50222
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sarah Liu <sarah@whamcloud.com>
Reviewed-by: Alex Deiter <alex.deiter@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>