Only require max_tokens when token rate limits apply

[GabrielBianconi]

Fix #3648

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Important

Modify rate limiting to require max_tokens only when token rate limits apply, updating RateLimitedRequest implementations and adding relevant tests.

• Behavior:
  • RateLimitedRequest trait's estimated_resource_usage method now takes resources parameter to determine if max_tokens is required.
  • EmbeddingRequest and ModelInferenceRequest implementations updated to conditionally require max_tokens based on RateLimitResource::Token presence.
  • RateLimitingConfig::get_rate_limited_resources method added to determine active rate-limited resources.
• Tests:
  • Added test_model_provider_infer_max_tokens_check in model.rs to validate behavior when max_tokens is missing or provided.
  • Added test_max_tokens_validation_with_rate_limits in rate_limiting/mod.rs to ensure correct resource inclusion based on rate limits.
• Misc:
  • Renamed RateLimitResourceUsage to EstimatedRateLimitResourceUsage in several places for clarity.

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[Copilot]

Pull Request Overview

This PR fixes issue #3648 by making the max_tokens parameter only required when token rate limits are actually active. The change introduces conditional validation that checks which rate limit resources are configured before requiring specific parameters.

Key changes:

• Added resource-aware validation for rate limiting requirements
• Replaced fixed resource usage calculation with conditional estimation based on active rate limits
• Updated the trait interface to pass rate-limited resources to estimation methods

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
tensorzero-core/src/rate_limiting/mod.rs	Adds method to get active rate-limited resources and updates resource usage calculation to be conditional
tensorzero-core/src/model.rs	Adds test coverage for max_tokens validation with different rate limiting configurations
tensorzero-core/src/inference/types/mod.rs	Updates ModelInferenceRequest to conditionally estimate token usage only when token rate limits are active
tensorzero-core/src/embeddings.rs	Updates EmbeddingRequest to conditionally estimate resource usage based on active rate limits

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[Copilot]

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Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

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[Copilot]

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Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull Request Overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

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