LU-17962 mgc: free nidlist correctly

LU-17962 mgc: free nidlist correctly

Memory leak was found during interop testing because
nidlist was not freed correctly in function
mgc_apply_recover_logs().

Test-Parameters: testlist=conf-sanity env=ONLY=29 \
  serverversion=2.15 clientdistro=el8.10 serverdistro=el8.10 \
  mdscount=2 mdtcount=4 ostcount=8

Fixes: e4d2d4ff74 ("LU-13306 mgc: handle large NID formats")
Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: I7a7a1b4b4f3b8c65c7608537e4dca1b9f1b68e77
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56709
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>