[DOCS] Remove experimental language from HDR Histo percentiles/ranks (#81773)

per issue 60780, decision from team to remove experimental language from HDR Histogram percentiles and ranks. Feature has been in production for quite some time.
closes #60780

docs/reference/aggregations/metrics/percentile-aggregation.asciidoc

@@ -308,8 +308,6 @@ the TDigest will use less memory.
 
 ==== HDR Histogram
 
-NOTE: This setting exposes the internal implementation of HDR Histogram and the syntax may change in the future.
-
 https://github.com/HdrHistogram/HdrHistogram[HDR Histogram] (High Dynamic Range Histogram) is an alternative implementation
 that can be useful when calculating percentiles for latency measurements as it can be faster than the t-digest implementation
 with the trade-off of a larger memory footprint. This implementation maintains a fixed worse-case percentage error (specified

docs/reference/aggregations/metrics/percentile-rank-aggregation.asciidoc

@@ -170,8 +170,6 @@ GET latency/_search
 
 ==== HDR Histogram
 
-NOTE: This setting exposes the internal implementation of HDR Histogram and the syntax may change in the future.
-
 https://github.com/HdrHistogram/HdrHistogram[HDR Histogram] (High Dynamic Range Histogram) is an alternative implementation
 that can be useful when calculating percentile ranks for latency measurements as it can be faster than the t-digest implementation
 with the trade-off of a larger memory footprint. This implementation maintains a fixed worse-case percentage error (specified as a