Make list instead of set for ids of vpc data source

[niuzhenguo]

What this PR does / why we need it:

Which issue this PR fixes:
(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)
fixes #1141

Special notes for your reviewer:

Release note:

PR Checklist

• Tests added/passed.
• Documentation updated.
• Schema updated.

Acceptance Steps Performed

make testacc TEST=./huaweicloud/ TESTARGS='-run=TestAccVpcIdsV1DataSource'
...
=== RUN   TestAccVpcIdsV1DataSource_basic
=== PAUSE TestAccVpcIdsV1DataSource_basic
=== CONT  TestAccVpcIdsV1DataSource_basic
--- PASS: TestAccVpcIdsV1DataSource_basic (109.59s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud       109.618s

make testacc TEST=./huaweicloud/ TESTARGS='-run=TestAccVpcRouteIdsV2DataSource'
...
=== RUN   TestAccVpcRouteIdsV2DataSource_basic
=== PAUSE TestAccVpcRouteIdsV2DataSource_basic
=== CONT  TestAccVpcRouteIdsV2DataSource_basic
--- PASS: TestAccVpcRouteIdsV2DataSource_basic (218.21s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud       218.235s

make testacc TEST=./huaweicloud/ TESTARGS='-run=TestAccVpcSubnetIdsV2DataSource'
...
=== RUN   TestAccVpcSubnetIdsV2DataSource_basic
=== PAUSE TestAccVpcSubnetIdsV2DataSource_basic
=== CONT  TestAccVpcSubnetIdsV2DataSource_basic
--- PASS: TestAccVpcSubnetIdsV2DataSource_basic (201.55s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud       201.573s