remove state transition from error to fence state

remove state transition from error to fence state

Remove the possible transition from error to fence state. The error
state is an end state and mustn't be left by some automatic action
but on manual intervention!

This also allows us later on to place a service which is not
recoverable from the fence in the error state without generating
and endless loop of state changes.

Add a regression test for a failed node with a service in error
state.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>