Revert "go testfixtures: test non-native SQL type in sqlgen/livesql"

This reverts commit 221d180.

internal/testfixtures/custom_type.go

@@ -5,28 +5,25 @@ import (
 	"fmt"
 )
 
-type CustomType [16]byte
+type CustomType []byte
 
 func CustomTypeFromString(s string) CustomType {
-	b := []byte(s)
-	c := CustomType{}
-	copy(c[:], b)
-	return c
+	return CustomType(s)
 }
 
 func (u CustomType) Value() (driver.Value, error) {
-	return []byte(u[:]), nil
+	return []byte(u), nil
 }
 
 func (u *CustomType) Scan(value interface{}) error {
 	switch value := value.(type) {
 	case nil:
 		u = nil
-	case string:
-		b := []byte(value)
-		copy(u[:], b)
 	case []byte:
-		copy(u[:], value)
+		*u = make(CustomType, len(value))
+		copy(*u, value)
+	case string:
+		*u = CustomType(value)
 	default:
 		return fmt.Errorf("cannot convert %v (of type %T) to %T", value, value, u)
 	}