MDEV-25591 : Test case cleanups

galera_var_wsrep_on_off : Add wait conditions to make sure DDL is
replicated before continuing.

wsrep.[variables|variables_debug] :  Remove unnecessary parts
and add check to correct number of variables or skip

galera_ssl_reload: Add version check and SSL checks.

mysql-test/suite/wsrep/r/variables_debug.result

@@ -0,0 +1,139 @@
+# Correct Galera library found
+SHOW GLOBAL STATUS LIKE 'wsrep%';
+Variable_name	Value
+wsrep_local_state_uuid	#
+wsrep_protocol_version	#
+wsrep_last_committed	#
+wsrep_replicated	#
+wsrep_replicated_bytes	#
+wsrep_repl_keys	#
+wsrep_repl_keys_bytes	#
+wsrep_repl_data_bytes	#
+wsrep_repl_other_bytes	#
+wsrep_received	#
+wsrep_received_bytes	#
+wsrep_local_commits	#
+wsrep_local_cert_failures	#
+wsrep_local_replays	#
+wsrep_local_send_queue	#
+wsrep_local_send_queue_max	#
+wsrep_local_send_queue_min	#
+wsrep_local_send_queue_avg	#
+wsrep_local_recv_queue	#
+wsrep_local_recv_queue_max	#
+wsrep_local_recv_queue_min	#
+wsrep_local_recv_queue_avg	#
+wsrep_local_cached_downto	#
+wsrep_flow_control_paused_ns	#
+wsrep_flow_control_paused	#
+wsrep_flow_control_sent	#
+wsrep_flow_control_recv	#
+wsrep_flow_control_active	#
+wsrep_flow_control_requested	#
+wsrep_cert_deps_distance	#
+wsrep_apply_oooe	#
+wsrep_apply_oool	#
+wsrep_apply_window	#
+wsrep_commit_oooe	#
+wsrep_commit_oool	#
+wsrep_commit_window	#
+wsrep_local_state	#
+wsrep_local_state_comment	#
+wsrep_cert_index_size	#
+wsrep_causal_reads	#
+wsrep_cert_interval	#
+wsrep_open_transactions	#
+wsrep_open_connections	#
+wsrep_incoming_addresses	#
+wsrep_cluster_weight	#
+wsrep_debug_sync_waiters	#
+wsrep_desync_count	#
+wsrep_evs_delayed	#
+wsrep_evs_evict_list	#
+wsrep_evs_repl_latency	#
+wsrep_evs_state	#
+wsrep_gcomm_uuid	#
+wsrep_gmcast_segment	#
+wsrep_applier_thread_count	#
+wsrep_cluster_capabilities	#
+wsrep_cluster_conf_id	#
+wsrep_cluster_size	#
+wsrep_cluster_state_uuid	#
+wsrep_cluster_status	#
+wsrep_connected	#
+wsrep_local_bf_aborts	#
+wsrep_local_index	#
+wsrep_provider_capabilities	#
+wsrep_provider_name	#
+wsrep_provider_vendor	#
+wsrep_provider_version	#
+wsrep_ready	#
+wsrep_rollbacker_thread_count	#
+wsrep_thread_count	#
+# Should show nothing.
+SHOW STATUS LIKE 'x';
+Variable_name	Value
+SELECT @@global.wsrep_cluster_address;
+@@global.wsrep_cluster_address
+gcomm://
+SELECT @@global.wsrep_on;
+@@global.wsrep_on
+1
+SHOW STATUS LIKE 'threads_connected';
+Variable_name	Value
+Threads_connected	1
+SHOW STATUS LIKE 'wsrep_thread_count';
+Variable_name	Value
+wsrep_thread_count	2
+# variables
+SELECT VARIABLE_NAME FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME LIKE "wsrep%" ORDER BY VARIABLE_NAME;
+VARIABLE_NAME
+WSREP_AUTO_INCREMENT_CONTROL
+WSREP_CAUSAL_READS
+WSREP_CERTIFICATION_RULES
+WSREP_CERTIFY_NONPK
+WSREP_CLUSTER_ADDRESS
+WSREP_CLUSTER_NAME
+WSREP_CONVERT_LOCK_TO_TRX
+WSREP_DATA_HOME_DIR
+WSREP_DBUG_OPTION
+WSREP_DEBUG
+WSREP_DESYNC
+WSREP_DIRTY_READS
+WSREP_DRUPAL_282555_WORKAROUND
+WSREP_FORCED_BINLOG_FORMAT
+WSREP_GTID_DOMAIN_ID
+WSREP_GTID_MODE
+WSREP_IGNORE_APPLY_ERRORS
+WSREP_LOAD_DATA_SPLITTING
+WSREP_LOG_CONFLICTS
+WSREP_MAX_WS_ROWS
+WSREP_MAX_WS_SIZE
+WSREP_MYSQL_REPLICATION_BUNDLE
+WSREP_NODE_ADDRESS
+WSREP_NODE_INCOMING_ADDRESS
+WSREP_NODE_NAME
+WSREP_NOTIFY_CMD
+WSREP_ON
+WSREP_OSU_METHOD
+WSREP_PATCH_VERSION
+WSREP_PROVIDER
+WSREP_PROVIDER_OPTIONS
+WSREP_RECOVER
+WSREP_REJECT_QUERIES
+WSREP_REPLICATE_MYISAM
+WSREP_RESTART_SLAVE
+WSREP_RETRY_AUTOCOMMIT
+WSREP_SLAVE_FK_CHECKS
+WSREP_SLAVE_THREADS
+WSREP_SLAVE_UK_CHECKS
+WSREP_SR_STORE
+WSREP_SST_AUTH
+WSREP_SST_DONOR
+WSREP_SST_DONOR_REJECTS_QUERIES
+WSREP_SST_METHOD
+WSREP_SST_RECEIVE_ADDRESS
+WSREP_START_POSITION
+WSREP_SYNC_WAIT
+WSREP_TRX_FRAGMENT_SIZE
+WSREP_TRX_FRAGMENT_UNIT