Revert "Deprecate `collection_cache_key` which is private API"

This reverts commit f656bb301a43fe441af0039e4fafe40a7faa62f8.

Reason: Test in Action View expects the `collection_cache_key` working...

https://github.com/rails/rails/blob/ff6b713f5e729859995f204093ad3f8e08f39ea8/actionview/test/activerecord/relation_cache_test.rb#L21
https://github.com/rails/rails/blob/ff6b713f5e729859995f204093ad3f8e08f39ea8/actionview/test/fixtures/project.rb#L6

https://buildkite.com/rails/rails/builds/60609#d19181fb-fe80-4d1e-891c-1109b540fb4b/981-1009

3 files changed, 2 insertions, 6 deletions

diff --git a/activerecord/lib/active_record/integration.rb b/activerecord/lib/active_record/integration.rb
index 810b6884f1..573a823dbc 100644
--- a/activerecord/lib/active_record/integration.rb
+++ b/activerecord/lib/active_record/integration.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require "active_support/core_ext/string/filters"
-require "active_support/deprecation"
 
 module ActiveRecord
   module Integration
@@ -165,7 +164,6 @@ module ActiveRecord
       def collection_cache_key(collection = all, timestamp_column = :updated_at) # :nodoc:
         collection.send(:compute_cache_key, timestamp_column)
       end
-      deprecate :collection_cache_key
     end
 
     private
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index b3a1b69293..ab24f67a6d 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -310,7 +310,7 @@ module ActiveRecord
     #   Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at)
     def cache_key(timestamp_column = :updated_at)
       @cache_keys ||= {}
-      @cache_keys[timestamp_column] ||= compute_cache_key(timestamp_column)
+      @cache_keys[timestamp_column] ||= klass.collection_cache_key(self, timestamp_column)
     end
 
     def compute_cache_key(timestamp_column = :updated_at) # :nodoc:
diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb
index f01bc0d7f1..f07f3c42e6 100644
--- a/activerecord/test/cases/collection_cache_key_test.rb
+++ b/activerecord/test/cases/collection_cache_key_test.rb
@@ -13,9 +13,7 @@ module ActiveRecord
     fixtures :developers, :projects, :developers_projects, :topics, :comments, :posts
 
     test "collection_cache_key on model" do
-      assert_deprecated do
-        assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\z/, Developer.collection_cache_key)
-      end
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\z/, Developer.collection_cache_key)
     end
 
     test "cache_key for relation" do