InfluxDB: Introduce maxDataPoints setting for flux variable query editor (#87935)

* Introduce custom variable support

* Remove comment lines

* introduce maxDataPoints

* fix tests

* update

* fix unit tests

* remove new line

pkg/tsdb/influxdb/flux/executor.go

@@ -29,8 +29,13 @@ func executeQuery(ctx context.Context, logger log.Logger, query queryModel, runn
 		logger.Warn("Flux query failed", "err", err, "query", flux)
 		dr.Error = err
 	} else {
-		// we only enforce a larger number than maxDataPoints
-		maxPointsEnforced := int(float64(query.MaxDataPoints) * maxPointsEnforceFactor)
+		maxPointsEnforced := int(query.MaxDataPoints)
+		// The default value of MaxDataPoints is 100 when it is not set
+		// See https://github.com/grafana/grafana/blob/d69b19e431bfe31ff904a48826593e6fa79b7a5b/pkg/services/query/query.go#L322
+		// So if the default value is being used we fall back to the old logic.
+		if query.MaxDataPoints == 100 {
+			maxPointsEnforced *= int(maxPointsEnforceFactor)
+		}
 
 		dr = readDataFrames(logger, tables, maxPointsEnforced, maxSeries)