LU-7609 tests: fix sanity-krb5

LU-7609 tests: fix sanity-krb5

Fix various issues with sanity-krb5 test script:
- replace elan with $NETTYPE in test 99;
- start gss daemon on MGS in test 151.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I5056240f733e82a59d96543b08476a959449f29d
Reviewed-on: http://review.whamcloud.com/17727
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>