EX-9530 tests: fix issues in backport of LU-13569

EX-9530 tests: fix issues in backport of LU-13569

Backport of "LU-13569 tests: Check LNet Health recovery logic"
introduced adding of redundant lnets and drop rules.
Clean this up.

Test-Parameters: trivial testlist=sanity-lnet
Test-Parameters: trivial testlist=sanity-lnet clientversion=EXA6 serverversion=2.15
Fixes: 2b6f7a39 ("LU-13569 tests: Check LNet Health recovery logic")
Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: I1e2d5d31f77a29504182650be30f9db7087d82cc
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54939
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>