Tooltip in Time series, incorrect data shown on snap

### What happened? When having a Timeseries graph, using the tooltip to inspect your data shows incorrect data (when using no interpolation) ### Result The _actual_ y value of the snapped measurement is shown in the tooltip (good) The _current_ time position of the cursor is shown in the tooltip (bad) ### What did you expect to happen? The _actual_ time value of the snapped point is shown in the tooltip. ### Did this work before? (much) older timeseries panel did this correct. (eg: grafana 9.2.1) ### Notes Issue was discussued in #36346 too The current behavior could make sense for graphs where you have interpolation. In case your have have graph with just points, I never makes sense to show data where: one of the coordinates is snapped to an actual point, but the other one displaying the position of your cursor. ### How do we reproduce it? 1. Create a timeseries graph, without interpolation. 2. graph has 'sparse' data (to make problem more visible) 3. hover your mouse around a data point <img width="523" height="203" alt="Image" src="https://github.com/user-attachments/assets/b38d3d43-1005-4634-beae-aa11c00b511d" /> ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? Grafana: 12.3.1 OS: any Browser: any ### Grafana platform? A package manager (APT, YUM, BREW, etc.) ### Datasource(s)? _No response_