Fix test result.

in 10.3, AWS encryption key was loaded during recovery, by the innodb purge
thread, therefore no note "loaded key" was written by the foreground
thread.

mysql-test/suite/mariabackup/xb_aws_key_management.result

@@ -11,6 +11,4 @@ INSERT INTO t VALUES('foobar1');
 SELECT * from t;
 c
 foobar1
-Warnings:
-Note	1105	AWS KMS plugin: loaded key 1, version 1, key length 128 bit
 DROP TABLE t;