TimeSeries: Default to single hover point (#102323)

Co-authored-by: Leon Sorokin <leeoniya@gmail.com>

public/app/core/components/GraphNG/__snapshots__/utils.test.ts.snap

@@ -75,6 +75,7 @@ exports[`GraphNG utils preparePlotConfigBuilder 1`] = `
     },
     "points": {
       "fill": [Function],
+      "one": true,
       "size": [Function],
       "stroke": [Function],
       "width": [Function],

public/app/core/components/TimeSeries/utils.ts

@@ -576,6 +576,7 @@ export const preparePlotConfigBuilder: UPlotConfigPrepFn = ({
     focus: {
       prox: hoverProximity ?? DEFAULT_FOCUS_PROXIMITY,
     },
+    points: { one: true },
   };
 
   builder.setCursor(cursor);