Backport ClickHouse#91923 to 25.8: Add a test for optimize_skip_unused_shards with type cast

Author: robot-clickhouse

tests/queries/0_stateless/03757_optimize_skip_unused_shards_with_type_cast.reference

@@ -0,0 +1,2 @@
+a
+b

tests/queries/0_stateless/03757_optimize_skip_unused_shards_with_type_cast.sql

@@ -0,0 +1,6 @@
+drop table if exists t1;
+
+create table t1 (Col LowCardinality(String)) engine = MergeTree;
+insert into t1 values ('a'), ('b'), ('c');
+
+select * from remote('127.{1,2}', currentDatabase(), t1, multiIf(Col = 'a', 0, Col = 'b', 1, -1)) where Col in ('a', 'b') order by all settings optimize_skip_unused_shards=1;