Fix cluster destroy failure
Fix cluster destroy failure

Cluster destroy would fail if there were errors while deactivating the
master IP address. This patch demotes such errors to warnings, allowing
the cluster to be destroyed even if the master IP address turndown
fails.

Signed-off-by: Andrea Spadaccini <92d490849ac1b40cd8e8878e4d94603bebdb089f@google.com>
Reviewed-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>
Reviewed-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

apyrgio/snf-ganeti,onponomarev/ganeti,apyrgio/ganeti,grnet/snf-ganeti,yiannist/ganeti,mbakke/ganeti,dimara/ganeti,bitemyapp/ganeti,ganeti/ganeti,leshchevds/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,onponomarev/ganeti,grnet/snf-ganeti,apyrgio/ganeti,andir/ganeti,yiannist/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,leshchevds/ganeti,leshchevds/ganeti,dimara/ganeti,andir/ganeti,ganeti/ganeti