Improve SampleGasPricesService tests

[mcmire]

Explanation

• Improve test names
• Don't assume default degraded threshold, but use constant
• Don't wait when advancing timers so we don't need an extra .catch(console.error)
• Ensure that maxRetries and maxConsecutiveFailures options are tested as well

References

No tickets, but I was reviewing someone's PR and noticed some anti-patterns and deficiencies in the current tests.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Test-only changes: renames/clarifies assertions around degraded/retry/circuit-break behavior and makes timer advancement deterministic, with no production code impact.

Overview
Improves SampleGasPricesService test coverage and clarity around service-policy behavior (degraded detection, retries, circuit breaker open/close).

Tests now use DEFAULT_DEGRADED_THRESHOLD instead of a hardcoded value, advance Jest timers synchronously (removing async .catch workarounds), and add explicit coverage that policyOptions like degradedThreshold, maxRetries, and maxConsecutiveFailures are configurable.

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