Optimizing API calls from /series to label/values

[Loori-R]

Problem:
The efficiency of the Grafana dashboard is deteriorating due to the use of the suboptimal /series API call. A more effective approach would be the use of the label/values call.

Solution:
To improve performance, it is necessary to adjust the logic for determining which API to use. It is important to minimize the use of the /series call in favor of more efficient methods.

Addition:
It may also be beneficial to implement a selector for choosing variable types, similar to what is used in Prometheus. This will allow for more accurate and efficient API interaction.

[Loori-R]

@hagen1778, what do you think about implementing a query type selector, as mentioned in the Addition section?

[Loori-R]

The enhancement has been included in victoriametrics-datasource v0.8.0.