EX-8450 tests: skip sanity-lipe-find3/306 on el7.9

EX-8450 tests: skip sanity-lipe-find3/306 on el7.9

The sanity-lipe-scan3 test_309 is failing consistently with el7.9
*clients*.  Exclude it until fixed or we drop this client version.

Test-Parameters: trivial testlist=sanity-lipe-find3 clientdistro=el7.9 serverdistro=el7.9
Test-Parameters: trivial testlist=sanity-lipe-find3 clientdistro=el8.8 serverdistro=el7.9
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Iceca83a3b85df95fe45482076170d77a6abc0947
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53853
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Vitaliy Kuznetsov <vkuznetsov@ddn.com>
Reviewed-by: Colin Faber <cfaber@ddn.com>