Register TLS config when setting up the throttler's connection info

This ensures that the throttler's TLS config has been registered with
the mysql driver before any connections are attempted.

This is the second part of resolving the following TLS verify
error:

2025-01-02 02:07:26 FATAL tls: failed to verify certificate: x509: certificate is valid for [old host], not [new host]

go/logic/throttler.go

@@ -216,6 +216,9 @@ func (this *Throttler) collectControlReplicasLag() {
 		lagResults := make(chan *mysql.ReplicationLagResult, instanceKeyMap.Len())
 		for replicaKey := range *instanceKeyMap {
 			connectionConfig := this.migrationContext.InspectorConnectionConfig.DuplicateCredentials(replicaKey)
+			if err := connectionConfig.RegisterTLSConfig(); err != nil {
+				return &mysql.ReplicationLagResult{Err: err}
+			}
 
 			lagResult := &mysql.ReplicationLagResult{Key: connectionConfig.Key}
 			go func() {