test(sparql-qlever): raise Docker-backed test timeouts to 120s

[ddeboer]

Summary

• The last 3 CI runs on main failed with @lde/sparql-qlever:test > test/server.test.ts > Server > start > starts and stops QLever timing out at 20s. The Docker-backed importer.test.ts (30s) trips on some runs too.
• Root cause: both tests use DockerTaskRunner.run(), which pulls adfreiburg/qlever:commit-a14e0a0 inline. On cold GitHub runners the pull alone exceeds the test budget.
• Fix: raise the per-test timeouts to 120s on the two tests that pull the QLever image. No CI-side coordination needed.

Test plan

• CI on this PR passes the @lde/sparql-qlever:test step.
• After merge, monitor the next main CI run to confirm the QLever timeout no longer recurs.