Fix: controller: really avoid closing attrd IPC for temporary failures

Since 35d69f2f (1.0.3), the controller attempts to connect to the
attribute manager and update an attribute multiple times before giving up.

b7c0e7f0 (1.1.9) attempted to avoid closing the IPC connection if the error
was "try again". However, rather than testing the errno from crm_ipc_connect(),
it tested the return value from attrd_update_delegate(), which would never
return that.

Refactor so we can check the right function's result. Also tweak log messages.