mgr/MgrMonitor: print pending.always_on_modules before updating it

mgr/MgrMonitor: print pending.always_on_modules before updating it

* early return to reduce the indent level for improve the readability
* print out the full `pending.always_on_modules` instead of the modules
  for current release, as we change it as long as the `map` does not
  match the one shipped in monitor, even if the discrepancy has no
  effects on current release.
* print `pending.always_on_modules` before updating it, to fix the
  logging message

Signed-off-by: Kefu Chai <kchai@redhat.com>