test: make the DECLARE conflict tests pass without a Java backend

[StephanWald]

The Publish Preview run for #691 (run 35957793016) failed in `verify`, and bump-version and both publishes were skipped.

Cause: two tests in `test/variable-scoping.test.ts` resolved `java.lang.String` and `java.lang.Integer` through the real Java interop on `localhost:5008`. Since #691, the conflicting-DECLARE check only reports a pair of classes when both resolve. An unresolved type is not treated as evidence of a conflict. CI has no backend, so the check stayed silent and both tests found no diagnostic. They passed locally only because BBjServices listens on :5008.

Fix: only the test changes, not the validator. The two tests now validate through `createBBjTestServices`. Its test double preloads `java.lang.String` and `java.util.HashMap`, an unrelated pair, and never opens a socket. The other 35 tests keep the real services.

Verified locally:

• The file passes 37/37 with :5008 up, and 37/37 when the regular services point at a closed port, which is what CI sees.
• Before the fix, the closed-port run reproduced exactly the 2 CI failures.
• With the validator temporarily changed to never report class conflicts, exactly these 2 tests fail, so they still catch a real regression.

🤖 Generated with Claude Code

[github-actions]

📦 Test build ready — bbj-lang-0.16.3-pr697-f92b872.vsix

Built from f92b872. Install it to try this PR without touching your Marketplace/preview build:

1. Download the VSIX artifact (a zip) and unzip it.
2. code --install-extension bbj-lang-0.16.3-pr697-f92b872.vsix — or Command Palette → Extensions: Install from VSIX…
3. Reload. To revert, uninstall it and reinstall the preview build.

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