Move the warning about composite primary key to `AttributeMethods::PrimaryKey`

Actually schema dumper/creation supports composite primary key (#21614).
Therefore it should not show the warning about composite primary key in
connection adapter.

This change moves the warning to `AttributeMethods::PrimaryKey` and
suppress the warning for habtm join table.

Fixes #25388.

1 files changed, 4 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
index 5fbd79d118..dd5fd607a2 100644
--- a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
@@ -76,8 +76,10 @@ module ActiveRecord::Associations::Builder # :nodoc:
           left_model.retrieve_connection
         end
 
-        def self.primary_key
-          false
+        private
+
+        def self.suppress_composite_primary_key(pk)
+          pk unless pk.is_a?(Array)
         end
       }