[Regression] Stacked series no longer sort according to legend in Time Series panel

### What is the regression? Sorting the legend in a Time Series panel with stacked series no longer reorders the stacked visualization to match. This feature was originally implemented in #9538 / PR #9563 for Grafana 5.0. ### When did it work? - Confirmed working: Grafana 8.3.0 - Confirmed broken: Grafana 8.5.9 and later (including 10.0.3+) ### Expected behavior When clicking legend column headers to sort (by min, max, avg, last, etc.), the stacked series in the visualization should reorder to match the legend sort order. ### Current behavior The legend sorts correctly, but the stacking order in the graph remains unchanged (appears to stay alphabetical or by query order). ### Why this matters This feature is vital for analyzing stacked charts where users need to quickly identify and compare the largest/smallest contributors. Without synchronized sorting, users must manually cross-reference the legend with the graph. ### Related issues/discussions - Original feature: #9538 (closed as completed in 5.0.0-beta1) - Community report: https://community.grafana.com/t/sorting-of-stacked-series-in-time-series-panel/69577