test: ValkeyDocumentStore removing duplicated tests already covered by haystack Mixin tests + allow non-schema-typed metadata values in Valkey get_metadata_field_unique_value

[davidsbatista]

Related Issues

• fixes https://github.com/deepset-ai/haystack-private/issues/501

Proposed Changes:

Fixes 4 integration test failures that surfaced after ValkeyDocumentStore started relying on Haystack's shared DocumentStore test mixin (ground truth for all doc stores), which expects behavior Valkey's
schema-based metadata didn't support:

• Unknown field no longer raises — get_metadata_field_unique_values()/_async used to raise ValueError when queried on a field not pre-configured for filtering. Since the values are already computed from
  the document's raw JSON payload (not the search index), this check was unnecessary — removed it. Querying an unknown field now correctly returns ([], 0).
• Type-mismatched writes no longer fail — writing a value that didn't match its field's configured index type (e.g. a string into a numeric field) used to raise ValueError and abort the whole write. Now
  the value is just omitted from the search index for that field/document, while the original value is still kept in the payload — so writes succeed and reads stay correct.
• Fixed a value-collapsing bug — unique values were deduplicated by their string form only, so 1, "1", 1.0, and True were incorrectly treated as the same value. Dedup now also checks the value's type,
  so these are kept distinct.

How did you test it?

• full local suite (make all: lint, mypy, unit, integration against a real Valkey container + CI

Notes for the reviewer

• No changes to the shared Haystack DocumentStore test mixin — only to ValkeyDocumentStore and Valkey-local tests.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

[github-actions]

Coverage report (valkey)

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/valkey/src/haystack_integrations/document_stores/valkey
document_store.py					1046, 1075-1077, 1326, 1491-1508
Project Total

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