MDEV-19514 fixup: Fix recovery with innodb_change_buffering_debug=1

During crash recovery, recv_sys.apply(true) invokes
mlog_init.mark_ibuf_exist(), which in turn may invoke
recv_sys.apply(true) via the buf_flush_sync() call in
buf_page_get_low(). The simplest fix is to disable the
innodb_change_buffering_debug=1 instrumentation
during crash recovery.

storage/innobase/buf/buf0buf.cc

@@ -3043,7 +3043,7 @@ buf_page_get_low(
 re_evict:
 	if (mode != BUF_GET_IF_IN_POOL
 	    && mode != BUF_GET_IF_IN_POOL_OR_WATCH) {
-	} else if (!ibuf_debug) {
+	} else if (!ibuf_debug || recv_recovery_is_on()) {
 	} else if (fil_space_t* space = fil_space_t::get(page_id.space())) {
 		/* Try to evict the block from the buffer pool, to use the
 		insert buffer (change buffer) as much as possible. */