Add capped collection tests

[danielfrankcom]

This change adds general tests for capped collections.

The aim here is to test the runtime semantics unique to capped collections like insertion ordering guarantees, natural sort behavior, eviction under size/max constraints, write-position stability across updates and upserts, and delete interactions.

I removed a duplicate smoke test file, and consolidated everything under the capped_collections dir. More extensive syntax tests for capped collections with commands like create and convertToCapped already live elsewhere in test files for those commands. The intent here is to only cover general semantic behavior of capped collections that apply more generally.

[documentdb-triage-tool]

🤖 Auto-triaged by documentdb-triage-tool.

Applied: compatibility test, enhancement
Project fields suggested: Component test-coverage · Priority P2 · Effort L · Status Needs Review
Confidence: 0.88 (mixed)

Reasoning

component from path globs (test-coverage); effort from diff stats (850+22 LOC, 7 files); LLM: Adds new test coverage for capped collection runtime semantics (insertion ordering, eviction, natural sort, etc.) under the compatibility tests directory, consolidating and expanding existing tests.

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