AsyncCacheNonBlocking - Improve availability during replica movement

[aayush3011]

Description

The current AsyncCache on force refreshes removes the value. It then creates a new value and all incoming requests are stuck waiting for the new task to complete.

Issue If a single replica moves only 1 of the 4 replicas URIs is stale. The current async cache is blocking all requests until the value is updated. The 3 other replicas could be used to successfully complete requests.

Solution AsyncCacheNonBlocking was created. This async cache does not block requests on refresh. It instead returns the stale value until the refresh is complete. Then the refresh value is used to update the cache. Any request using the forceRefresh to true will wait on the same refresh task.

All SDK Contribution checklist:

• [ ] The pull request does not introduce [breaking changes]
• [ ] CHANGELOG is updated for new features, bug fixes or other significant changes.
• [ ] I have read the contribution guidelines.

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Testing Guidelines

• [x] Pull request includes test coverage for the included changes.
• [x] Benchmark Tests
• [x] Benchmark Tests:

RU: 100,000, Documents: 100,000, Region: South Central US

Throughput:

P95 Latency

P99 Latency

P999 Latency

Max Latency

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