MDEV-38195: Fix flaky events_restart and tmp_space_usage tests

events.events_restart: Add missing error log suppressions for
"error during compilation" and "Query was empty" that occur when
the event scheduler processes events from a corrupted mysql.event
table (body column altered to longtext).

main.tmp_space_usage: The test compares tmp_space_used from
session_status and processlist, but reads them at different times
across a connection switch. Internal temp space changes (e.g. InnoDB
page allocation) between reads cause small differences. Allow up to
32KB tolerance (two InnoDB pages) instead of requiring exact equality.

Signed-off-by: Varun Deep Saini <varun.23bcs10048@ms.sst.scaler.com>

Author: Varun Deep Saini

mysql-test/main/tmp_space_usage.test

@@ -107,11 +107,14 @@ let $tmp_usage1=`select variable_value from information_schema.session_status wh
 connection c1;
 --disable_query_log
 let $tmp_usage2=`select tmp_space_used from information_schema.processlist where id=$id`;
-if ($tmp_usage1 == $tmp_usage2)
+# The two values are read at slightly different times, so they may differ
+# by a small amount due to internal temp space changes between reads.
+let $diff=`select abs(cast('$tmp_usage1' as signed) - cast('$tmp_usage2' as signed))`;
+if ($diff <= 32768)
 {
 --echo # information_schema.process_list.tmp_space_used == status.tmp_space_used
 }
-if ($tmp_usage1 != $tmp_usage2)
+if ($diff > 32768)
 {
 --echo tmp_space_used difference: $tmp_usage1 != $tmp_usage2
 }

mysql-test/suite/events/events_restart.test

@@ -4,6 +4,8 @@
 call mtr.add_suppression('Column count of mysql.event is wrong. Expected .*, found .*\. The table is probably corrupted');
 call mtr.add_suppression('Event Scheduler: An error occurred when initializing system tables. Disabling the Event Scheduler');
 call mtr.add_suppression('Event Scheduler.*shutdown.*');
+call mtr.add_suppression('Event Scheduler: error during compilation of');
+call mtr.add_suppression('Event Scheduler:.*Query was empty');
 --enable_query_log
 
 let $collation_server=`select @@collation_server`;