Implicit through table joins should be appeared before user supplied joins

#36293 was an issue for through association with `joins` for a long
time, but since #35864 through association with `left_joins` would also
be affected by the issue.

Implicit through table joins should be appeared before user supplied
joins, otherwise loading through association with joins will cause a
statement invalid error.

Fixes #36293.

```
% ARCONN=postgresql bundle exec ruby -w -Itest test/cases/associations/has_many_through_associations_test
.rb -n test_through_association_with_joins
Using postgresql
Run options: -n test_through_association_with_joins --seed 7116

# Running:

E

Error:
HasManyThroughAssociationsTest#test_through_association_with_joins:
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  missing FROM-clause entry for table "posts"
LINE 1: ... "comments_posts" ON "comments_posts"."post_id" = "posts"."i...
                                                             ^
: SELECT "comments".* FROM "comments" INNER JOIN "comments" "comments_posts" ON "comments_posts"."post_id" = "posts"."id" INNER JOIN "posts" ON "comments"."post_id" = "posts"."id" WHERE "posts"."author_id" = $1

rails test test/cases/associations/has_many_through_associations_test.rb:61

Finished in 0.388657s, 2.5730 runs/s, 0.0000 assertions/s.
1 runs, 0 assertions, 0 failures, 1 errors, 0 skips
```

1 files changed, 11 insertions, 17 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index b8fd2fce14..50ff733dc7 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -1128,27 +1128,21 @@ module ActiveRecord
 
         association_joins = buckets[:association_join]
         stashed_joins     = buckets[:stashed_join]
-        join_nodes        = buckets[:join_node].uniq
-        string_joins      = buckets[:string_join].map(&:strip).uniq
+        join_nodes        = buckets[:join_node].tap(&:uniq!)
+        string_joins      = buckets[:string_join].delete_if(&:blank?).map!(&:strip).tap(&:uniq!)
 
-        join_list = join_nodes + convert_join_strings_to_ast(string_joins)
-        alias_tracker = alias_tracker(join_list, aliases)
+        string_joins.map! { |join| table.create_string_join(Arel.sql(join)) }
 
-        join_dependency = construct_join_dependency(association_joins, join_type)
+        join_sources = manager.join_sources
+        join_sources.concat(join_nodes) unless join_nodes.empty?
 
-        joins = join_dependency.join_constraints(stashed_joins, alias_tracker)
-        joins.each { |join| manager.from(join) }
-
-        manager.join_sources.concat(join_list)
-
-        alias_tracker.aliases
-      end
+        unless association_joins.empty? && stashed_joins.empty?
+          alias_tracker = alias_tracker(join_nodes + string_joins, aliases)
+          join_dependency = construct_join_dependency(association_joins, join_type)
+          join_sources.concat(join_dependency.join_constraints(stashed_joins, alias_tracker))
+        end
 
-      def convert_join_strings_to_ast(joins)
-        joins
-          .flatten
-          .reject(&:blank?)
-          .map { |join| table.create_string_join(Arel.sql(join)) }
+        join_sources.concat(string_joins) unless string_joins.empty?
       end
 
       def build_select(arel)