Time series graph: Disconnect threshold not limited to interval

### What happened? Here's a graph of ping results: <img width="1601" height="696" alt="Image" src="https://github.com/user-attachments/assets/62dc6427-57a3-4e9f-a182-636a7a11ba13" /> The pings are done every second, but the data source respects the interval (it uses `$__timeInterval_ms()`), so the data source delivers one point (per series) for every 15s in this example. The disconnect threshold is set to 5s and it causes all the points to be disconnected. ### What did you expect to happen? While technically it's not _wrong_ to disconnect the points when they are further apart than the disconnect interval, it's not at all helpful. This was discussed previously in https://github.com/grafana/grafana/issues/83031 and as far as I understand interval is supposed to limit the disconnect threshold. In other words, the actual, effective disconnect threshold is supposed to be the maximum of the interval and the set disconnect threshold. https://github.com/grafana/grafana/issues/83031 was closed as resolved, but there are many comments that it isn't and I can confirm that the issue still exists in 12.3.1. ### Did this work before? I don't think so. ### How do we reproduce it? 1. Go to any interval-aware time series graph that provides data at regular intervals. 2. Set a disconnect threshold that is currently above the interval, i.e. if the interval is 1s, set a disconnect threshold of 2s. 3. Increase the time range, so that the interval increases, for example from 1s to 15s. 4. Note how all the dots are now disconnected. ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? Grafana: 12.3.1 OS: Docker on Ubuntu Browser: Chrome 144 ### Grafana platform? Docker ### Datasource(s)? _No response_