SamplingStatCalculator#addSample resulting value takes time to compute, and it is rarely used

### Use case

`org.apache.jmeter.visualizers.SamplingStatCalculator#addSample` computes `mean`, `median`, `50%` (in addition to `median`), and the values are typically ignored.

https://github.com/apache/jmeter/blob/049cc3a69443b218eaec761b56ada221842e46d0/src/core/src/main/java/org/apache/jmeter/visualizers/SamplingStatCalculator.java#L199-L211

Here's how the resulting value is ignored:
https://github.com/apache/jmeter/blob/049cc3a69443b218eaec761b56ada221842e46d0/src/components/src/main/java/org/apache/jmeter/visualizers/StatVisualizer.java#L124-L133

### Possible solution

Create separate methods for updating and retrieving the values.
It might make sense to use `LongAdder` or even `HdrHistogram` for the summary.

It might make sense to combine `SamplingStatCalculator` and `Calculator`

### Possible workarounds

_No response_

### JMeter Version

5.5

### Java Version

_No response_

### OS Version

_No response_

### See also

* https://github.com/apache/jmeter/pull/380
* https://github.com/apache/jmeter/issues/5769