Fix `change_column` to drop default with `null: false`

Currently `change_column` cannot drop default if `null: false` is
specified at the same time. This change fixes the issue.

```ruby
  # cannot drop default
  change_column "tests", "contributor", :boolean, default: nil, null: false

  # we need the following workaround currently
  change_column "tests", "contributor", :boolean, null: false
  change_column "tests", "contributor", :boolean, default: nil
```

Closes #26582

1 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 5f86a11c2d..f14ac92cf9 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -786,11 +786,11 @@ module ActiveRecord
         def change_column_sql(table_name, column_name, type, options = {})
           column = column_for(table_name, column_name)
 
-          unless options_include_default?(options)
+          unless options.key?(:default)
             options[:default] = column.default
           end
 
-          unless options.has_key?(:null)
+          unless options.key?(:null)
             options[:null] = column.null
           end