Histogram standard mode csv tests (elastic#139773)

In this PR:

- expand the histogram sample data by including the data from the t-digest sample index, reformatted for the histogram field
- replicate the standard mode tests from the t-digest into the histogram csv tests, with the addition of casting the histogram to a t-digest
- merge the development capabilities for histogram type down to a single capability (I've tagged it with test-release to get some confidence this was done correctly)

Author: not-napoleon

x-pack/plugin/esql/qa/server/src/main/java/org/elasticsearch/xpack/esql/qa/rest/EsqlSpecTestCase.java

@@ -321,7 +321,7 @@ protected boolean supportsTDigestField() {
     }
 
     protected boolean supportsHistogramDataType() {
-        return RestEsqlTestCase.hasCapabilities(client(), List.of(EsqlCapabilities.Cap.HISTOGRAM_FIELD_SUPPORT_V0.capabilityName()));
+        return RestEsqlTestCase.hasCapabilities(client(), List.of(EsqlCapabilities.Cap.HISTOGRAM_RELEASE_VERSION.capabilityName()));
     }
 
     protected boolean supportsBFloat16ElementType() {