Larger offset when calculating the next histogram bucket to avoid col… (elastic#139675) (elastic#139737)

We generate legacy histograms in `DownsampleIT` and we used to small of
a delta when generating the histogram values which caused them to
collide. We ensure that the delta between the buckets is more than 1.0
fix that.

Fixes  elastic#139382

(cherry picked from commit 7ac049f)

# Conflicts:
#	muted-tests.yml

Author: gmarouli

muted-tests.yml

@@ -400,9 +400,6 @@ tests:
 - class: org.elasticsearch.smoketest.SmokeTestMultiNodeClientYamlTestSuiteIT
   method: test {yaml=index/100_field_name_length_limit/Test field name length limit array synthetic source}
   issue: https://github.com/elastic/elasticsearch/issues/139300
-- class: org.elasticsearch.xpack.downsample.DownsampleIT
-  method: testAggregateMethod
-  issue: https://github.com/elastic/elasticsearch/issues/139382
 - class: org.elasticsearch.xpack.inference.integration.AuthorizationTaskExecutorIT
   method: testCreatesChatCompletion_AndThenCreatesTextEmbedding
   issue: https://github.com/elastic/elasticsearch/issues/138012

x-pack/plugin/downsample/src/internalClusterTest/java/org/elasticsearch/xpack/downsample/DownsampleIT.java

@@ -646,7 +646,7 @@ private static double[] randomHistogramValues(int size) {
         final double[] array = new double[size];
         double minHistogramValue = randomDoubleBetween(0.0, 0.1, true);
         for (int i = 0; i < array.length; i++) {
-            array[i] = minHistogramValue += randomDoubleBetween(0.0, 0.5, true);
+            array[i] = minHistogramValue += randomDoubleBetween(0.1, 10.0, true);
         }
         return array;
     }