LU-17971 gss: do not make lsvcgss record its PID

LU-17971 gss: do not make lsvcgss record its PID

The lsvcgssd daemon is expected to spawn a few additional threads at
startup to carry out extra work. In this case finding the PID of the
'main' thread can be complicated.
So do not try to record this by ourselves, and let systemctl handle
that.

Test-Parameters: trivial
Test-Parameters: testgroup=review-dne-selinux-ssk-part-1
Test-Parameters: testgroup=review-dne-selinux-ssk-part-2
Test-Parameters: kerberos=true testlist=sanity-krb5
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I7ddfcd5b5f3c69a46079b42d76fb9585953e30b1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55509
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>