Fix GROUP BY queries to apply LIMIT/OFFSET after aggregations

If `eager_loading` is true, `apply_join_dependency` force applies
LIMIT/OFFSET before JOINs by `limited_ids_for` to keep parent records
count. But for aggregation queries, LIMIT/OFFSET should be applied after
aggregations the same as SQL semantics.

And also, we could not replace SELECT list by `limited_ids_for` when a
query has a GROUP BY clause. It had never been worked since it will
causes generating invalid SQL for MySQL, PostgreSQL, and probably most
backends.

```
% ARCONN=postgresql be ruby -w -Itest test/cases/calculations_test.rb -n test_group_by_with_limit
Using postgresql
Run options: -n test_group_by_with_limit --seed 20925

# Running:

E

Error:
CalculationsTest#test_group_by_with_limit:
ActiveRecord::StatementInvalid: PG::GroupingError: ERROR:  column "posts.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT  DISTINCT "posts"."id", "posts"."type" AS alias_0 FRO...                         ^
: SELECT  DISTINCT "posts"."id", "posts"."type" AS alias_0 FROM "posts" LEFT OUTER JOIN "comments" ON "comments"."post_id" = "posts"."id" GROUP BY "posts"."type" ORDER BY "posts"."type" ASC LIMIT $1
```

Fixes #8103.
Closes #27249.

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index f7613a187d..31fb8ce0e5 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -379,7 +379,7 @@ module ActiveRecord
         )
       end
 
-      def apply_join_dependency(eager_loading: true)
+      def apply_join_dependency(eager_loading: group_values.empty?)
         join_dependency = construct_join_dependency
         relation = except(:includes, :eager_load, :preload).joins!(join_dependency)