Mute org.elasticsearch.xpack.sql.expression.function.scalar.datetime.DateTimeToCharProcessorTests

relates elastic#120575

Author: rjernst

muted-tests.yml

@@ -465,3 +465,5 @@ tests:
 - class: org.elasticsearch.oldrepos.OldRepositoryAccessIT
   method: testOldRepoAccess
   issue: https://github.com/elastic/elasticsearch/issues/120148
+- class: org.elasticsearch.xpack.sql.expression.function.scalar.datetime.DateTimeToCharProcessorTests
+  issue: https://github.com/elastic/elasticsearch/issues/120575