Coverage UT can time out downloading unused Adopt JDK 8 before tests

[XuPeng-SH]

Summary

MatrixOne Coverage UT can fail before package discovery because its Set up Go step enables the shared setup-env action's Java 8 installer. In MatrixOne #29290 rebased Coverage job, actions/setup-java@v4 spent about 9m31s downloading Adopt JDK 8 from GitHub and hit the step's 10-minute timeout. No Go tests ran.

Owner and evidence

.github/workflows/coverage-ut.yaml calls matrixorigin/CI/actions/setup-env@main with setup-java: true. The Coverage helper scripts and native preparation do not invoke Java. The only repository Go tests found launching Java are optional datastream E2E cases; they skip if the jstfu jar is absent, and this Coverage workflow does not build that jar. The workflow can therefore avoid the remote JDK download by disabling Java setup for Coverage UT. This does not change Java setup for BVT or jobs that actually require it.

Acceptance

• Remove Java setup from the Coverage UT job while keeping Go/CMake/native setup intact.
• Validate the reusable workflow syntax and confirm the Coverage job reaches Go test execution on a MatrixOne PR.
• Keep the optional datastream Java cases' existing skip/required behavior unchanged.