Remove unused ParsedAggregation (#104848)

This abstraction was introduced to support the high level rest client and is not needed any more.

Author: iverase

client/rest-high-level/src/main/java/org/elasticsearch/client/analytics/ParsedStringStats.java

@@ -22,8 +22,4 @@
     opens org.elasticsearch.aggregations to org.elasticsearch.painless.spi; // whitelist resource access
 
     provides org.elasticsearch.painless.spi.PainlessExtension with org.elasticsearch.aggregations.AggregationsPainlessExtension;
-
-    provides org.elasticsearch.plugins.spi.NamedXContentProvider
-        with
-            org.elasticsearch.aggregations.metric.MatrixStatsNamedXContentProvider;
 }