[Feature] enable hugegraph-struct tests in CI

[contrueCT]

Feature Description (功能描述)

Currently hugegraph-struct is built in PR CI as an upstream dependency, but its tests are not executed by default. In pd-store-ci.yml, the module is built with:

mvn -DskipTests -pl hugegraph-struct -am install

This means regressions covered only by hugegraph-struct tests can be missed by the default CI workflow.

Since hugegraph-struct is intended to become the shared source of truth for common data structures and query abstractions, it would be helpful to add CI coverage for its test suite.

Expected outcome:

• run hugegraph-struct tests in PR CI
• catch regressions in struct-side logic earlier
• keep the existing pd/store downstream workflow working as before

[contrueCT]

I plan to follow up on this issue with a dedicated PR.