Improve TraceQL metrics topk rendering

This issue is most apparent when using the topk function, but likely occurs in other cases. When using topk with TraceQL metrics, disconnected sections of the line are connected. The green arrow points to a connection that should not be visible in the time series panel. <img width="5004" height="1370" alt="Image" src="https://github.com/user-attachments/assets/8e95da2a-78fb-40d4-b339-dff7a168fdbe" /> Compare this to a similar query in promql. In this query lines are only drawn between contiguous points in the series: <img width="5068" height="1422" alt="Image" src="https://github.com/user-attachments/assets/1a8cf6d3-5ceb-4777-97bf-44e7926d57a8" /> See example dataframes below. In both cases you will see the series' timestamps/values passed as arrays of values. In both cases the "missing" points are the same. They are simply omitted from the data. There are differences between the two, but I'm not sure how to interpret these differences. For instance the promql dataframe has a different "typeVersion". Ultimately we'd simply like the promql rendering over the traceql rendering. If there's something different that Tempo can return to make this happen, let us know. <details> <summary>promql dataframe</summary> ``` [ { "schema": { "refId": "A", "meta": { "type": "timeseries-multi", "typeVersion": [ 0, 1 ], "custom": { "calculatedMinStep": 60000, "resultType": "matrix" }, "executedQueryString": "Expr: topk(1, sum(rate(tempo_distributor_bytes_received_total{namespace=\"tempo-dev-02\"}[1m])) by (pod))\nStep: 1m0s", "preferredVisualisationType": "graph" }, "fields": [ { "name": "Time", "type": "time", "typeInfo": { "frame": "time.Time" }, "config": { "interval": 60000 } }, { "na…