fix(dms): fix import func for rabbitmq vhost exchange queue

[saf3dfsa]

What this PR does / why we need it: fix import func for rabbitmq vhost exchange queue

PR Checklist

• [x] Tests added/passed.

./scripts/acc-test.sh 

run acceptance tests of huaweicloud/services/acceptance/dms/resource_huaweicloud_dms_rabbitmq_exchange_test.go:
=== RUN   TestAccRabbitmqExchange_basic
=== PAUSE TestAccRabbitmqExchange_basic
=== RUN   TestAccRabbitmqExchange_slash
=== PAUSE TestAccRabbitmqExchange_slash
=== CONT  TestAccRabbitmqExchange_basic
=== CONT  TestAccRabbitmqExchange_slash
--- PASS: TestAccRabbitmqExchange_slash (805.41s)
--- PASS: TestAccRabbitmqExchange_basic (901.69s)
PASS
coverage: 9.8% of statements in ./huaweicloud/services/dms
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dms       901.756s        coverage: 9.8% of statements in ./huaweicloud/services/dms

run acceptance tests of huaweicloud/services/acceptance/dms/resource_huaweicloud_dms_rabbitmq_queue_test.go:
=== RUN   TestAccRabbitmqQueue_basic
=== PAUSE TestAccRabbitmqQueue_basic
=== RUN   TestAccRabbitmqQueue_slash
=== PAUSE TestAccRabbitmqQueue_slash
=== CONT  TestAccRabbitmqQueue_basic
=== CONT  TestAccRabbitmqQueue_slash
--- PASS: TestAccRabbitmqQueue_slash (775.06s)
--- PASS: TestAccRabbitmqQueue_basic (886.23s)
PASS
coverage: 9.8% of statements in ./huaweicloud/services/dms
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dms       886.304s        coverage: 9.8% of statements in ./huaweicloud/services/dms

run acceptance tests of huaweicloud/services/acceptance/dms/resource_huaweicloud_dms_rabbitmq_vhost_test.go:
=== RUN   TestAccRabbitmqVhost_basic
=== PAUSE TestAccRabbitmqVhost_basic
=== RUN   TestAccRabbitmqVhost_slash
=== PAUSE TestAccRabbitmqVhost_slash
=== CONT  TestAccRabbitmqVhost_basic
=== CONT  TestAccRabbitmqVhost_slash
--- PASS: TestAccRabbitmqVhost_basic (796.39s)
--- PASS: TestAccRabbitmqVhost_slash (890.33s)
PASS
coverage: 8.3% of statements in ./huaweicloud/services/dms
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/dms       890.410s        coverage: 8.3% of statements in ./huaweicloud/services/dms

### coverage of files in huaweicloud/services:

- github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/dms/resource_huaweicloud_dms_rabbitmq_exchange.go (85.7%)
- github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/dms/resource_huaweicloud_dms_rabbitmq_queue.go (78.0%)
- github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/dms/resource_huaweicloud_dms_rabbitmq_vhost.go (84.6%)

### [summary] 0 failed in 3 resource acceptance tests

• [x] Documentation updated.
• [ ] Schema updated.

• [ ] CheckDeleted.

  • a. During query operation (Read Context) aa. Resource not found >>>>>> Paste the screenshot here <<<<<<
  • b. During delete/disassociate/unbind operation (Delete Context) ba. Resource not found >>>>>> Paste the screenshot here <<<<<<

[houpeng80]

/lgtm /approve