MDEV-32554 mon_lock_wait_current_count test causes innodb.monitor failure

This commit will be applied during 10.5->10.6 merging as a part of
conflicts resolution.

-------------------------
SET GLOBAL innodb_monitor_disable=all;
-------------------------

was set at the the beggining of mon_lock_wait_current_count test,
because lock_row_lock_time_avg is filled under lock_sys.wait_mutex lock,
which is held by connection 2:

--------------------------
--connect (con2,localhost,root,,)
SET DEBUG_SYNC="lock_wait_before_suspend SIGNAL blocked WAIT_FOR cont";
BEGIN;
--send SELECT * FROM t FOR UPDATE
-------------------------

That is why the followin SELECT is blocked:

-----------------------
SELECT name, count FROM information_schema.innodb_metrics
  WHERE name ='lock_row_lock_current_waits';
-----------------------

And setting innodb_monitor_disable=all causes innodb monitor enabling
status changing. And the status is not restored to default value even
after
-----------------------
SET GLOBAL innodb_monitor_reset_all=default;
SET GLOBAL innodb_monitor_enable=default;
-----------------------
execution. See MDEV-32553 for details.

The fix is to disable not all the monitors at the beggining of the test,
but only the monitor, which causes hanging, i.e. lock_row_lock_time_avg.

MDEV-32553 it the root case, the current fix is just workaround.
10.5 is not affected, as there is difference in innodb.monitor.

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

 connect  prevent_purge,localhost,root,,;
 START TRANSACTION WITH CONSISTENT SNAPSHOT;
 connection default;
-SET GLOBAL innodb_monitor_disable='all';
-SET GLOBAL innodb_monitor_enable='lock_row_lock_current_waits';
+SET GLOBAL innodb_monitor_disable='lock_row_lock_time_avg';
 CREATE TABLE `t` (a INT PRIMARY KEY) engine=InnoDB STATS_PERSISTENT=0;
 INSERT INTO t VALUES (5);
 SELECT name, count FROM information_schema.innodb_metrics
@@ -48,6 +47,7 @@ DROP TABLE `t`;
 SET GLOBAL innodb_monitor_disable='lock_row_lock_current_waits';
 SET GLOBAL innodb_monitor_reset_all='lock_row_lock_current_waits';
 SET GLOBAL innodb_monitor_enable='lock_row_lock_current_waits';
+SET GLOBAL innodb_monitor_enable='lock_row_lock_time_avg';
 SET GLOBAL innodb_monitor_disable=default;
 SET GLOBAL innodb_monitor_reset_all=default;
 SET GLOBAL innodb_monitor_enable=default;

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

@@ -10,8 +10,27 @@
 START TRANSACTION WITH CONSISTENT SNAPSHOT;
 
 --connection default
-SET GLOBAL innodb_monitor_disable='all';
-SET GLOBAL innodb_monitor_enable='lock_row_lock_current_waits';
+# lock_row_lock_time_avg is filled under lock_sys.wait_mutex lock, which
+# will be held by connection 2, that is why the following SELECT
+# from information_schema.innodb_metrics will be blocked.
+#
+# And setting innodb_monitor_disable=all causes innodb monitor enabling
+# status changing. The status will not be restored to default value even
+# after
+# -----------------------
+# SET GLOBAL innodb_monitor_reset_all=default;
+# SET GLOBAL innodb_monitor_enable=default;
+# -----------------------
+# execution. See MDEV-32553 for details.
+#
+# All monitors disabling, i.e. "innodb_monitor_disable=all" causes
+# innodb.monitor test failure due to MDEV-32553. 10.5 is not affected, as
+# innodb.monitor differs there.
+#
+# Disable not all monitors at the beggining of the test,
+# but only the monitor, which causes hanging, i.e. lock_row_lock_time_avg.
+SET GLOBAL innodb_monitor_disable='lock_row_lock_time_avg';
+# 'lock_row_lock_current_waits' should be enabled by default;
 CREATE TABLE `t` (a INT PRIMARY KEY) engine=InnoDB STATS_PERSISTENT=0;
 INSERT INTO t VALUES (5);
 SELECT name, count FROM information_schema.innodb_metrics
@@ -67,6 +86,8 @@ DROP TABLE `t`;
 SET GLOBAL innodb_monitor_disable='lock_row_lock_current_waits';
 SET GLOBAL innodb_monitor_reset_all='lock_row_lock_current_waits';
 SET GLOBAL innodb_monitor_enable='lock_row_lock_current_waits';
+# TODO: remove it when MDEV-32553 is fixed
+SET GLOBAL innodb_monitor_enable='lock_row_lock_time_avg';
 --disable_warnings
 SET GLOBAL innodb_monitor_disable=default;
 SET GLOBAL innodb_monitor_reset_all=default;