fix(aggregate): request top occurrence values over gRPC

[ktz03]

Metrics("title").text(top_occurrences_value=True) currently writes top_occurences=False in the gRPC text aggregation request, so requesting values without occurrence counts does not enable the requested aggregation. Enable the wire flag when either counts or values are requested, matching the GraphQL selection behavior.

The regression tests exercise the public collection.aggregate.over_all() API, mock only the final transport call, and round-trip the actual protobuf requests. They cover all text metric flag combinations, both with and without a top-occurrence limit.

Validation on Windows with Python 3.11.16:

• Focused aggregation tests: 17 passed. The 16 new cases yield 4 failures and 12 passing controls on unchanged main, and all pass with the fix.
• Ruff 0.14.7 lint/format and Flake8 with the repository's plugins pass for both changed files. Pyright 1.1.399 reports no errors for the changed source file.
• Full pytest test with PYTHONUTF8=1: 542 passed, 1 skipped, and 2 timeout-diagnostic stderr assertion failures. Unchanged main reproduces the same two failures (526 passed, 1 skipped).

A running Weaviate server and model inference were not tested.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

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