MDEV-27476 heap-use-after-free in buf_pool_t::is_block_field()

mtr_t::modify(): Remove a debug assertion that had been added
in commit 05fa4558 (MDEV-22110).
The function buf_pool_t::is_uncompressed() is only safe to invoke
while holding a buf_pool.page_hash latch so that buf_pool_t::resize()
cannot concurrently invoke free() on any chunks.

storage/innobase/mtr/mtr0mtr.cc

 /*****************************************************************************
 
 Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, 2021, MariaDB Corporation.
+Copyright (c) 2017, 2022, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -1217,7 +1217,6 @@ void mtr_t::modify(const buf_block_t &block)
   {
     /* This must be PageConverter::update_page() in IMPORT TABLESPACE. */
     ut_ad(!block.page.in_LRU_list);
-    ut_ad(!buf_pool.is_uncompressed(&block));
     return;
   }