net.box: update connection state before calling any triggers

Currently, the connection state is updated after calling triggers. However,
the triggers can, in turn, cause a new state change. The state will be
updated the state in the wrong order, and the original state change will
overwrite the state change from the trigger. To fix this, let's update the
connection state before calling any triggers.

Closes #9827

NO_DOC=<bugfix>

(cherry picked from commit bb38b059)