ceph-nvmeof-mon fixes

ceph-nvmeof-mon fixes

- remove observer from NVMeofMon
  Signed-off-by: Leonid Chernin <leonidc@il.ibm.com>
  (cherry picked from commit a20fb90357990abac6d2696949e48ef4fa5a7880)

- fix assert issue in find_failback_gw - failover_peers array was removed
  Signed-off-by: Leonid Chernin <leonidc@il.ibm.com>
  (cherry picked from commit 4c6a9b3ed194eb7837e6b341aba227042e497078)

- try to resolve slow ops
  It seems that if monitor preprocess_query(MonOpRequestRef op) returns
  true, then  mon.reply_command() should be called. Remove path which
  returns true without mon.reply_command() call.
  (cherry picked from commit 99a345cb0d70851addc33aa3fa7fe07ed5d67b94)

  Resolves: rhbz#2272663

Signed-off-by: Alexander Indenbaum <aindenba@redhat.com>
(cherry picked from commit f0b748db48dbe704de320974c40ea851e8ac061f)