Follow up to #50733.

```
% diff -ub test/schema/mysql2_specific_schema.rb test/schema/trilogy_specific_schema.rb
--- test/schema/mysql2_specific_schema.rb       2024-09-07 19:53:07
+++ test/schema/trilogy_specific_schema.rb      2024-09-07 19:50:17
@@ -21,7 +21,6 @@
     t.string :char2, limit: 50, default: "a varchar field"
     if ActiveRecord::TestCase.supports_default_expression?
       t.binary :uuid, limit: 36, default: -> { "(uuid())" }
-      t.string :char2_concatenated, default: -> { "(concat(`char2`, '-'))" }
     end
   end

```