Removed unused code from tests

[trycatchkamal]

Removes unused test-related classes, functions, and types identified by static analysis

These symbols are not referenced anywhere in the codebase, including other tests

Used ts-prune to detect unused exports in the codebase

Manually verified that these symbols are not referenced anywhere else

Summary

Component	File
ChunkingEndpointClientCache, ISerializedFileChunk, ISerializedFileChunkWithEmbedding, ICacheEntry	test/base/cachingChunksEndpointClient.ts
CodeOrDocSearchCache, ICacheEntry	test/base/cachingCodeSearchClient.ts
EmbeddingsCache, ICacheEntry	test/base/embeddingsCache.ts
forEachCombination (function)	test/base/stest.ts
MockProgress (class)	test/base/testProgress.ts
assertDeepStrictEqualsAny	test/simulation/stestUtil.ts

[trycatchkamal]

@microsoft-github-policy-service agree

[mjbvz]

Thanks!