[Copilot]

Two L1 cache tests allow only 100 ms between insertion and a cache-hit assertion, causing spurious failures on busy CI runners.

• Factory lifetime: Use a 1 s lifetime and 3 s TTL, with waits that distinguish factory expiry from TTL capping.
• TTL expiry: Increase the TTL to 1 s and wait 1.5 s before checking expiry.
• Scope: Preserve every assertion; no production changes. Add a changelog fragment.

• Fixes Flaky tests: the cache's L1 TTL tests give an entry 100 ms to survive the next call #471

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[Copilot]

🟢 Approval recommended

The narrow test-only changes match the requested timing adjustments, preserve behavioral checks, and have no identified blocking issues.

No open issues 🎉

What changed in this PR

This PR addresses #471 by widening timing windows in two L1 cache tests to reduce CI flakes without changing production behavior or removing assertions.

Changes:

• Increase factory-lifetime and TTL windows, with waits that preserve lifetime-expiry and TTL-capping checks.
• Increase the TTL-expiry test’s TTL to 1 second and expiry wait to 1.5 seconds.
• Add a changelog fragment documenting the test reliability improvement.

File	Description
docs/​changes/​2.0.0/​471.fixed.md	Documents the wider test timing windows.
crates/​cache/​tests/​l1_unit.rs	Adjusts lifetimes, TTLs, waits, and messages while preserving assertions.

_{Review effort: Balanced}