Remove the often-hanging test innodb.alter_rename_files

The test innodb.alter_rename_files rather frequently hangs in
checkpoint_set_now. The test was removed in MariaDB Server 10.5
commit 37e7bde1 when the code that
it aimed to cover was simplified. Starting with MariaDB Server 10.5
the page flushing and log checkpointing is much simpler, handled
by the single buf_flush_page_cleaner() thread.

Let us remove the test to avoid occasional failures. We are not going
to fix the cause of the failure in MariaDB Server 10.4.

mysql-test/suite/innodb/r/alter_rename_files.result

-CREATE TABLE t1 (x INT NOT NULL UNIQUE KEY) ENGINE=InnoDB;
-INSERT INTO t1 VALUES(5);
-SET GLOBAL innodb_log_checkpoint_now=TRUE;
-SET DEBUG_SYNC='commit_cache_rebuild SIGNAL ready WAIT_FOR finish';
-ALTER TABLE t1 FORCE;;
-connect  con1,localhost,root,,;
-SET DEBUG_SYNC='now WAIT_FOR ready';
-SET GLOBAL innodb_log_checkpoint_now=TRUE;
-SET DEBUG_SYNC='now SIGNAL finish';
-disconnect con1;
-connection default;
-SHOW CREATE TABLE t1;
-Table	Create Table
-t1	CREATE TABLE `t1` (
-  `x` int(11) NOT NULL,
-  UNIQUE KEY `x` (`x`)
-) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
-DROP TABLE t1;
-SET DEBUG_SYNC='RESET';

mysql-test/suite/innodb/t/alter_rename_files.test

---source include/have_debug.inc
---source include/have_debug_sync.inc
---source include/have_innodb.inc
---source include/count_sessions.inc
-
-CREATE TABLE t1 (x INT NOT NULL UNIQUE KEY) ENGINE=InnoDB;
-INSERT INTO t1 VALUES(5);
-
-SET GLOBAL innodb_log_checkpoint_now=TRUE;
-
-# Start an ALTER TABLE and stop it before renaming the files
-SET DEBUG_SYNC='commit_cache_rebuild SIGNAL ready WAIT_FOR finish';
-
---send ALTER TABLE t1 FORCE;
-
-connect (con1,localhost,root,,);
-
-SET DEBUG_SYNC='now WAIT_FOR ready';
-
-SET GLOBAL innodb_log_checkpoint_now=TRUE;
-
-SET DEBUG_SYNC='now SIGNAL finish';
-
-disconnect con1;
-connection default;
-reap;
-SHOW CREATE TABLE t1;
-DROP TABLE t1;
-SET DEBUG_SYNC='RESET';
-
---source include/wait_until_count_sessions.inc