MDEV-14222 Unnecessary 'cascade' memory allocation for every updated row
when there is no FOREIGN KEY

This reverts the MySQL 5.7.2 change
https://github.com/mysql/mysql-server/commit/377774689bf6a16af74182753fe950d514c2c6dd
which introduced these problems. MariaDB 10.2.2 inherited these problems
in commit 2e814d47.

The FOREIGN KEY CASCADE and SET NULL operations implemented as
procedural recursion are consuming more than 8 kilobytes of stack
(9 stack frames) per iteration in a non-debug GNU/Linux AMD64 build.
This is why we need to limit the maximum recursion depth to 15 steps
instead of the 255 that it used to be in MySQL 5.7 and MariaDB 10.2.

A corresponding change was made in MySQL 5.7.21 in
https://github.com/mysql/mysql-server/commit/7b26dc98a624d5cdf79cd5eee455cb03e3bccb5a