Fix the hosted Java selector for 1.21.11 releases

[SkyBlade1978]

Summary

• keep java_toolchain_version=21.0.7+6 as the exact Temurin compiler/runtime identity
• add java_setup_version=21.0.7+6.0.LTS, the catalog selector required by actions/setup-java
• add a regression contract that requires both values and prevents them being conflated

Cause

Release run 33613753108 routed and validated 4.0.16.121111 correctly, then failed before Gradle started because GitHub's Temurin catalog exposes this build as 21.0.7+6.0.LTS, not the shorter 21.0.7+6 selector.

The shared dispatcher already supports a separate hosted setup selector. This target-specific metadata change leaves the dispatcher and the established Java 8, 16, 17, and other branch release paths unchanged.

Validation

• ReleaseWorkflowContractTest passed under the pinned Java 21/8/25 toolchains
• verifyReleaseConfiguration passed
• git diff --check passed
• the failed release created no tag and did not enter Maven, CurseForge, or GitHub publication

No production source, gameplay behavior, API/schema, artifact name, or release content changes.