A fix for Bug#27406 Events: failure only causes a warning. Update test

results.
When executing a CREATE EVENT statement with ON COMPLETION NOT PRESERVE 
clause (explicit or implicit) and completion date in the past, we do not 
create the event. Or, put it differently, we create it and then drop 
immediately.
A warning is issued in this case, not an error -- we want to load 
successfully old database dumps, and such dumps may contain events
that are no longer valid.

Update the warning text to not imply an erroneous condition. 

mysql-test/r/events_bugs.result

@@ -31,7 +31,7 @@ create event e_55 on schedule at 10000101000000 do drop table t;
 ERROR HY000: Incorrect AT value: '10000101000000'
 create event e_55 on schedule at 20000101000000 do drop table t;
 Warnings:
-Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created
+Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 show events;
 Db	Name	Definer	Time zone	Type	Execute at	Interval value	Interval field	Starts	Ends	Status	Originator	character_set_client	collation_connection	Database Collation
 create event e_55 on schedule at 20200101000000 starts 10000101000000 do drop table t;
@@ -447,32 +447,32 @@ e3		+00:00	CREATE EVENT `e3` ON SCHEDULE EVERY 1 DAY STARTS '2006-01-01 00:00:00
 The following should fail, and nothing should be altered.
 ALTER EVENT e1 ON SCHEDULE EVERY 1 HOUR STARTS '1999-01-01 00:00:00'
   ENDS '1999-01-02 00:00:00';
-ERROR HY000: Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been altered
+ERROR HY000: Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 ALTER EVENT e1 ON SCHEDULE EVERY 1 HOUR STARTS '1999-01-01 00:00:00'
   ENDS '1999-01-02 00:00:00' DISABLE;
-ERROR HY000: Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been altered
+ERROR HY000: Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 The following should give warnings, and nothing should be created.
 CREATE EVENT e4 ON SCHEDULE EVERY 1 HOUR STARTS '1999-01-01 00:00:00'
   ENDS '1999-01-02 00:00:00'
 DO
 SELECT 1;
 Warnings:
-Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created
+Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 CREATE EVENT e4 ON SCHEDULE EVERY 1 HOUR STARTS '1999-01-01 00:00:00'
   ENDS '1999-01-02 00:00:00' DISABLE
 DO
 SELECT 1;
 Warnings:
-Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created
+Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 CREATE EVENT e4 ON SCHEDULE AT '1999-01-01 00:00:00' DO
 SELECT 1;
 Warnings:
-Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created
+Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 CREATE EVENT e4 ON SCHEDULE AT '1999-01-01 00:00:00' DISABLE
 DO
 SELECT 1;
 Warnings:
-Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created
+Note	1584	Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation.
 SHOW EVENTS;
 Db	Name	Definer	Time zone	Type	Execute at	Interval value	Interval field	Starts	Ends	Status	Originator	character_set_client	collation_connection	Database Collation
 events_test	e1	root@localhost	+05:00	RECURRING	NULL	1	DAY	2006-01-01 00:00:00	NULL	ENABLED	1	latin1	latin1_swedish_ci	latin1_swedish_ci

sql/share/errmsg.txt

@@ -6052,9 +6052,9 @@ ER_BINLOG_PURGE_EMFILE
         eng "Too many files opened, please execute the command again"
         ger "Zu viele offene Dateien, bitte fhren Sie den Befehl noch einmal aus"
 ER_EVENT_CANNOT_CREATE_IN_THE_PAST
-        eng "Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been created"
+        eng "Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation."
 ER_EVENT_CANNOT_ALTER_IN_THE_PAST
-        eng "Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. Event has not been altered"
+        eng "Event execution time is in the past and ON COMPLETION NOT PRESERVE is set. The event was dropped immediately after creation."
 ER_SLAVE_INCIDENT
         eng "The incident %s occured on the master. Message: %-.64s"
 ER_NO_PARTITION_FOR_GIVEN_VALUE_SILENT