The counters were added in commit 5e55d1ce
and any code to update them was
inadvertently removed in commit 2e814d47
when applying InnoDB changes from MySQL 5.7.

Let us remove these counters that never reported anything useful. If such
statistics are really needed in a special case, they can be obtained by
instrumenting the code by some means, such as eBPF or a source code patch.