LU-18099 tests: disable userns checking in sanity-pcc/101a

LU-18099 tests: disable userns checking in sanity-pcc/101a

ubuntu 24.04 has an additional security restriction on
unprivileged user namespace. Disable it in sanity-pcc/101a
temporarily on ubuntu2404 or later version.

Signed-off-by: Feng Lei <flei@whamcloud.com>
Test-Parameters: trivial
Test-Parameters: clientdistro=ubuntu2404 testlist=sanity-pcc env=ONLY=101a,ONLY_REPEAT=10
Change-Id: I9da81dc02e0784f4e40f1d4d276588fb354a481c
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56312
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>