Revert shell version to 8.0.21 until 8.0.22 is available

Change-Id: I766978d45f242f4cf78ced67890aead8e8d7350a

Author: bkandasa

VERSION

@@ -4,8 +4,8 @@ MYSQL_CLUSTER_VERSIONS["7.5"]=7.5.20
 MYSQL_CLUSTER_VERSIONS["7.6"]=7.6.16
 MYSQL_CLUSTER_VERSIONS["8.0"]=8.0.22
 declare -A MYSQL_SHELL_VERSIONS
-MYSQL_SHELL_VERSIONS["7.5"]=8.0.22
-MYSQL_SHELL_VERSIONS["7.6"]=8.0.22
+MYSQL_SHELL_VERSIONS["7.5"]=8.0.21
+MYSQL_SHELL_VERSIONS["7.6"]=8.0.21
 MYSQL_SHELL_VERSIONS["8.0"]=8.0.21
 
 declare -A SERVER_VERSION_FULL