`Scene/Vector3DTileClampedPolylines` specs causing CI to fail during coverage

A bunch of different branches started failing in CI very recently with the same timeouts during coverage:

```
1) renders clamped polylines
Scene/Vector3DTileClampedPolylines
Error: Timeout - Async function did not complete within 30000ms (set by jasmine.DEFAULT_TIMEOUT_INTERVAL) in node_modules/jasmine-core/lib/jasmine-core/jasmine.js (line 7741)

2) picks a clamped polyline
Scene/Vector3DTileClampedPolylines
Error: Timeout - Async function did not complete within 30000ms (set by jasmine.DEFAULT_TIMEOUT_INTERVAL) in node_modules/jasmine-core/lib/jasmine-core/jasmine.js (line 7741)

```

This doesn't appear related to any recent code changes and I'm not sure yet why this started happening. As a fallback plan we can always disable these tests in CI but probably worth looking into some more first. I cannot reproduce this locally.

Start with the Scene/Vector3DTileClampedPolylines specs and the coverage CI job that runs them. Reproduce the two Jasmine timeout failures in CI or inspect the coverage configuration and test output to identify why these async tests do not complete. Done means the tests no longer cause coverage CI timeouts, or the issue documents an agreed safe handling for them.

Written by the indexing model from the issue text.