MDEV-25524 heap-use-after-free in fil_space_t::rename()

In commit 91599701d0 (MDEV-25312)
some recovery code for TRUNCATE TABLE was broken
causing a regression in a case where undo log for a RENAME TABLE
operation had been durably written but the tablespace had not been
renamed yet.

row_rename_table_for_mysql(): Add a DEBUG_SYNC point for the
test case, and simplify the logic and trim the error messages.

fil_space_t::rename(): Simplify the operation. Merge the necessary
part of fil_rename_tablespace_check(). If there is no change to
the file name, do nothing.

dict_table_t::rename_tablespace(): Refactored from
dict_table_rename_in_cache().

row_undo_ins_parse_undo_rec(): On rolling back TRX_UNDO_RENAME_TABLE,
invoke dict_table_t::rename_tablespace() even if the table name matches.

os_file_rename_func(): Temporarily relax an assertion that would
fail during the recovery in the test innodb.truncate_crash.

storage/innobase/include/dict0mem.h

@@ -2045,6 +2045,12 @@ struct dict_table_t {
   void stats_mutex_lock() { lock_mutex_lock(); }
   void stats_mutex_unlock() { lock_mutex_unlock(); }
 
+  /** Rename the data file.
+  @param new_name     name of the table
+  @param replace      whether to replace the file with the new name
+                      (as part of rolling back TRUNCATE) */
+  dberr_t rename_tablespace(const char *new_name, bool replace) const;
+
 private:
 	/** Initialize instant->field_map.
 	@param[in]	table	table definition to copy from */