MDEV-21979 Galera test sporadic failure on galera_3nodes.galera_pc_weight (#1473)

Forcing wait on nodes 2 and 3, to turn wsrep_ready to 'ON' before querying wsrep status variables.
This guarantees that status reads don't come too early on these nodes

mysql-test/suite/galera_3nodes/r/galera_pc_weight.result

@@ -87,6 +87,8 @@ SET GLOBAL wsrep_provider_options = 'gmcast.isolate=0';
 connection node_2;
 connection node_3;
 connection node_1;
+connection node_2;
+connection node_3;
 SELECT VARIABLE_VALUE = 3 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_size';
 VARIABLE_VALUE = 3
 1

mysql-test/suite/galera_3nodes/t/galera_pc_weight.test

@@ -88,6 +88,15 @@ SET GLOBAL wsrep_provider_options = 'gmcast.isolate=0';
 --connection node_1
 --source include/wait_condition.inc
 
+# wait until nodes 2 and 3 have declared ready state (can happen after cluster_size raaise)
+--connection node_2
+--let $wait_condition = SELECT VARIABLE_VALUE = 'ON' FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_ready'
+--source include/wait_condition.inc
+
+--connection node_3
+--source include/wait_condition.inc
+
+
 # On all nodes, we now expect a Primary component of size 3, weight 3, Synced and ready
 SELECT VARIABLE_VALUE = 3 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_size';
 SELECT VARIABLE_VALUE = 3 FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME = 'wsrep_cluster_weight';