Fix test scripts to use mc ready (#19768)

buildscripts/disable-root.sh

@@ -32,6 +32,7 @@ fi
 set +e
 
 export MC_HOST_minioadm=http://minioadmin:minioadmin@localhost:9100/
+./mc ready minioadm
 
 ./mc ls minioadm/
 

buildscripts/minio-iam-ldap-upgrade-import-test.sh

@@ -56,6 +56,7 @@ create_iam_content_in_old_minio() {
 
 	set -x
 	mc alias set old-minio http://localhost:9000 minioadmin minioadmin
+	mc ready old-minio
 	mc idp ldap add old-minio \
 		server_addr=localhost:1389 \
 		server_insecure=on \
@@ -87,6 +88,7 @@ import_iam_content_in_new_minio() {
 	set -x
 	mc alias set new-minio http://localhost:9000 minioadmin minioadmin
 	echo "BEFORE IMPORT mappings:"
+	mc ready new-minio
 	mc idp ldap policy entities new-minio
 	mc admin cluster iam import new-minio ./old-minio-iam-info.zip
 	echo "AFTER IMPORT mappings:"