Rename some new experimental settings

Author: davenger

src/Core/Settings.cpp

@@ -6716,19 +6716,19 @@ Allow experimental delta-kernel-rs implementation.
     DECLARE(Bool, make_distributed_plan, false, R"(
 Make distributed query plan.
 )", EXPERIMENTAL) \
-    DECLARE(Bool, execute_distributed_plan_locally, false, R"(
+    DECLARE(Bool, distributed_plan_execute_locally, false, R"(
 Run all tasks of a distributed query plan locally. Useful for testing and debugging.
 )", EXPERIMENTAL) \
-    DECLARE(UInt64, default_shuffle_join_bucket_count, 8, R"(
+    DECLARE(UInt64, distributed_plan_default_shuffle_join_bucket_count, 8, R"(
 Default number of buckets for distributed shuffle-hash-join.
 )", EXPERIMENTAL) \
-    DECLARE(UInt64, default_reader_bucket_count, 8, R"(
+    DECLARE(UInt64, distributed_plan_default_reader_bucket_count, 8, R"(
 Default number of tasks for parallel reading in distributed query. Tasks are spread across between replicas.
 )", EXPERIMENTAL) \
-    DECLARE(Bool, optimize_exchanges, false, R"(
+    DECLARE(Bool, distributed_plan_optimize_exchanges, true, R"(
 Removes unnecessary exchanges in distributed query plan. Disable it for debugging.
 )", EXPERIMENTAL) \
-    DECLARE(String, force_exchange_kind, "", R"(
+    DECLARE(String, distributed_plan_force_exchange_kind, "", R"(
 Force specified kind of Exchange operators between distributed query stages.
 
 Possible values: