MM-45159: Skip flaky TestCreateUserWithInitialPreferences (#20489)

https://mattermost.atlassian.net/browse/MM-45159

```release-note
NONE
```

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/user_test.go

@@ -1725,6 +1725,7 @@ func TestUpdateThreadReadForUser(t *testing.T) {
 }
 
 func TestCreateUserWithInitialPreferences(t *testing.T) {
+	t.Skip("MM-45159")
 	th := Setup(t).InitBasic()
 	defer th.TearDown()