LU-16848 gss: drop legacy 'lgssd' and pipefs code

LU-16848 gss: drop legacy 'lgssd' and pipefs code

Get rid of the old 'lgssd' code which is unused
for a while, and not even buildable.

Test-Parameters: trivial
Test-Parameters: testlist=sanity-sec
Test-Parameters: kerberos=true testlist=sanity-krb5

Change-Id: I821cc5b625e97c7f5fdc758b166bd54e5e4b379e
Signed-off-by: Aurelien Degremont <adegremont@nvidia.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51032
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>