[Chore] Remove order-dependent runtime listener test

[roomote-roomote]

​Created by Roomote. View the task or mention @roomote-roomote for follow-up asks.

​Created by Roomote. Follow up by mentioning @roomote-roomote or in the web UI.

What changed

Removed the test that only checked global process signal-listener counts after a separate test leased a server.

Why this change was made

The assertion depended on test order and verified a private implementation detail rather than shutdown behavior. The retained process-tree shutdown test exercises the observable cleanup regression directly.

Impact

No production behavior or public contract changes. The test suite has one fewer order-dependent, maintenance-heavy case while preserving meaningful OpenCode server shutdown coverage.

Validation

• opencode-runtime.test.ts: 26 passed.
• Fast-agent bridge and service overlap tests: 40 passed.
• @roomote/cloud-agents typecheck passed.
• Package formatting and targeted oxlint passed.
• Pre-push checks passed: oxlint, residual lint, fast typecheck, and knip.

[roomote-community]

No code issues found. See task

_{Reviewed 2e6a4cd}