Faster, more reliable suite shard planning

The CLI no longer boots every test bundle’s runner to enumerate suites when planning suite-level shards. The server now produces the shard plan from the built .xctestrun module list plus historical test data, removing the slow and flaky xcodebuild -enumerate-tests step that could fail under simulator contention or stretch builds toward an hour when most modules had to be recovered one by one. The final shard now acts as a catch-all, so newly added, renamed, or otherwise unknown suites still run instead of being silently dropped.