GODT-1474: Optimising live integration tests

- pkg/pmapi: Reduce max number of retries
- test/features: tweak create mailbox scenarios.
- test/context: change order of clean up steps
- test/context: logger field
- test/context: message preparation per username
- test/context: check that eventID has changed after adding messages
- test/features: make sure we wait 15sec before detecting import duplicates

test/fakeapi/controller_control.go

@@ -230,7 +230,7 @@ func (ctl *Controller) GetAuthClient(username string) pmapi.Client {
 }
 
 // LockEvents doesn't needs to be implemented for fakeAPI.
-func (ctl *Controller) LockEvents() {}
+func (ctl *Controller) LockEvents(string) {}
 
 // UnlockEvents doesn't needs to be implemented for fakeAPI.
-func (ctl *Controller) UnlockEvents() {}
+func (ctl *Controller) UnlockEvents(string) {}