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/context/pmapi_controller.go

@@ -43,8 +43,8 @@ type PMAPIController interface {
 	WasCalled(method, path string, expectedRequest []byte) bool
 	WasCalledRegex(methodRegex, pathRegex string, expectedRequest []byte) (bool, error)
 	GetCalls(method, path string) [][]byte
-	LockEvents()
-	UnlockEvents()
+	LockEvents(username string)
+	UnlockEvents(username string)
 }
 
 func newPMAPIController(listener listener.Listener) (PMAPIController, pmapi.Manager) {