Replace timer-based TTL expiration tests with fake clock

[waveywaves]

Context

In PR #9051, we implemented a shared resolver cache with TTL-based expiration. The current unit tests for TTL expiration use time.Sleep() to wait for cache entries to expire, which makes tests slower and potentially flaky.

Task

Replace the timer-based approach in TestCacheTTLExpiration with a fake clock implementation.

Current Implementation

The test currently uses:

time.Sleep(ttl + (100 * time.Millisecond))

Proposed Solution

• Use the existing fakeClock type that's already in the cache package
• Inject the fake clock into the cache instance
• Advance the clock programmatically instead of sleeping
• This will make tests faster, more deterministic, and less flaky

Files to Modify

• pkg/remoteresolution/resolver/framework/cache/cache_test.go (TestCacheTTLExpiration)

References

• Original PR: feat: implement shared cache for bundle, git, and cluster resolvers #9051
• Feedback from @twoGiants requesting this improvement