LU-6632 mgs: dont remove EXCLUDE records on lctl replace_nids

LU-6632 mgs: dont remove EXCLUDE records on lctl replace_nids

conf-sanity.sh:test_66 is modified to illustrate the problem:
  add EXCLUDE records to config file. lctl replace_nids removes
  those records which leads to mounting problem
fix: Remove records marked as SKIP instead of EXCLUDE ones.

Change-Id: Ica4b23a74870d8ebcb09b240313df4d4c33bbbde
Signed-off-by: Vladimir Saveliev <c17830@cray.com>
Signed-off-by: Alyona Romanenko <alyona.romanenko@seagate.com>
Cray-bug-id: MRP-2105
Cray-bug-id: MRP-2766
Reviewed-by: Sergey Cheremencev <c17829@cray.com>
Reviewed-by: Artem Blagodarenko <c17828@cray.com>
Test-Parameters: trivial envdefinitions=ONLY=66 testlist=conf-sanity
Reviewed-on: https://review.whamcloud.com/14921
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Elena Gryaznova <c17455@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>