fix(dms): fix updating public IP ID for rocketmq instance

[saf3dfsa]

What this PR does / why we need it: fix updating public IP ID for rocketmq instance

PR Checklist

• [x] Tests added/passed.
• [x] Documentation updated.
• [x] Schema updated.

Acceptance Steps Performed

make testacc TEST="./huaweicloud/services/acceptance/dms" TESTARGS="-run TestAccDmsRocketMQInstance_broker_publicip"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/dms -v -run TestAccDmsRocketMQInstance_broker_publicip -timeout 360m -parallel 4
=== RUN   TestAccDmsRocketMQInstance_broker_publicip
=== PAUSE TestAccDmsRocketMQInstance_broker_publicip
=== CONT  TestAccDmsRocketMQInstance_broker_publicip
--- PASS: TestAccDmsRocketMQInstance_broker_publicip (1638.89s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dms       1638.979s