Use HDR for percentiles (#64758)

Author: sorenlouv

x-pack/plugins/apm/server/lib/transaction_groups/__snapshots__/fetcher.test.ts.snap

@@ -83,7 +83,11 @@ export function transactionGroupsFetcher(
             sample: { top_hits: { size: 1, sort } },
             avg: { avg: { field: TRANSACTION_DURATION } },
             p95: {
-              percentiles: { field: TRANSACTION_DURATION, percents: [95] }
+              percentiles: {
+                field: TRANSACTION_DURATION,
+                percents: [95],
+                hdr: { number_of_significant_value_digits: 2 }
+              }
             },
             sum: { sum: { field: TRANSACTION_DURATION } }
           }

x-pack/plugins/apm/server/lib/transaction_groups/__snapshots__/queries.test.ts.snap

@@ -69,7 +69,11 @@ export function timeseriesFetcher({
           aggs: {
             avg: { avg: { field: TRANSACTION_DURATION } },
             pct: {
-              percentiles: { field: TRANSACTION_DURATION, percents: [95, 99] }
+              percentiles: {
+                field: TRANSACTION_DURATION,
+                percents: [95, 99],
+                hdr: { number_of_significant_value_digits: 2 }
+              }
             }
           }
         },

x-pack/plugins/apm/server/lib/transaction_groups/fetcher.ts

@@ -86,6 +86,7 @@ export interface AggregationOptionsByType {
   percentiles: {
     field: string;
     percents?: number[];
+    hdr?: { number_of_significant_value_digits: number };
   };
   extended_stats: {
     field: string;