Adapt from 10.2: git cherry-pick bfb5e1c3f0ba57b54f245d7cc2d1dfabaa7c4462
buf_pool_t::chunk_t::create(), buf_pool_t::resize():
Restore or simplify the debug instrumentation.
buf_resize_callback(): Add DBUG_ENTER/DBUG_VOID_RETURN so that
the DBUG_EXECUTE_IF in buf_pool_t::resize() can be triggered.