Unmute FieldSortIT testSortMixedFieldTypes (#130755)

Author: cbuescher

muted-tests.yml

@@ -549,9 +549,6 @@ tests:
 - class: org.elasticsearch.indices.stats.IndexStatsIT
   method: testFilterCacheStats
   issue: https://github.com/elastic/elasticsearch/issues/124447
-- class: org.elasticsearch.search.sort.FieldSortIT
-  method: testSortMixedFieldTypes
-  issue: https://github.com/elastic/elasticsearch/issues/129445
 - class: org.elasticsearch.xpack.esql.action.CrossClusterAsyncQueryStopIT
   method: testStopQueryLocal
   issue: https://github.com/elastic/elasticsearch/issues/121672