Intermediate changes

commit_hash:5dc37859843b869f97de12bf0119c647c4076f9f

Author: robot-piglet

yql/essentials/cfg/tests/gateways-experimental.conf

@@ -91,7 +91,6 @@ YqlCore {
     Flags {
         Name: "OptimizerFlags"
         Args: [
-            "FieldSubsetEnableMultiusage",
             "MemberNthOverFlatMap",
             "ExtractMembersSplitOnOptional",
             "FilterNullMembersOverJust",

yt/yql/tests/sql/suites/aggregate/group_by_ru_join_simple_fs_multiusage.sql

@@ -2,5 +2,4 @@
 /* postgres can not */
 
 pragma sampleselect;
-pragma config.flags("OptimizerFlags", "FieldSubsetEnableMultiusage");
 select kk, sk, max(t2.subkey) as ss FROM plato.Input AS t1 INNER JOIN plato.Input AS t2 USING (key) GROUP BY ROLLUP(t1.key as kk, t1.subkey as sk) ORDER BY kk, sk;

yt/yql/tests/sql/suites/optimizers/length_over_merge_fs_multiusage.sql

@@ -1,6 +1,4 @@
 /* postgres can not */
-pragma config.flags("OptimizerFlags", "FieldSubsetEnableMultiusage");
-
 use plato;
 
 $input = (select key, key || subkey as subkey, value from Input);

yt/yql/tests/sql/suites/optimizers/yql-18408_filter_multiusage_pushdown.sql

@@ -1,7 +1,6 @@
 use plato;
 pragma AnsiOptionalAs;
 pragma config.flags("OptimizerFlags",
-                    "FieldSubsetEnableMultiusage",
                     "FilterPushdownEnableMultiusage",
                     "EarlyExpandSkipNull");