fix: initialize available_tokens to max_bucket_size

[LincolnBurrows2017]

Fixed rate limiter to allow bursting on first request

[codspeed-hq]

Merging this PR will improve performance by 30.84%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 13 improved benchmarks
⏩ 23 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	test_import_time[CallbackManager]	336.1 ms	262.2 ms	+28.2%
⚡	WallTime	test_import_time[ChatPromptTemplate]	677.3 ms	529.5 ms	+27.91%
⚡	WallTime	test_import_time[LangChainTracer]	480.7 ms	373.7 ms	+28.61%
⚡	WallTime	test_import_time[PydanticOutputParser]	565.5 ms	446.9 ms	+26.52%
⚡	WallTime	test_async_callbacks_in_sync	25.2 ms	20 ms	+26.04%
⚡	WallTime	test_import_time[HumanMessage]	277.3 ms	214.8 ms	+29.07%
⚡	WallTime	test_import_time[Runnable]	522.8 ms	406.3 ms	+28.69%
⚡	WallTime	test_import_time[Document]	200.2 ms	154 ms	+29.95%
⚡	WallTime	test_import_time[InMemoryRateLimiter]	181.2 ms	141.9 ms	+27.68%
⚡	WallTime	test_import_time[tool]	582.2 ms	458.2 ms	+27.05%
⚡	WallTime	test_import_time[BaseChatModel]	573.4 ms	438.2 ms	+30.84%
⚡	WallTime	test_import_time[InMemoryVectorStore]	643.7 ms	503.4 ms	+27.87%
⚡	WallTime	test_import_time[RunnableLambda]	522.3 ms	404.4 ms	+29.15%

---

_{Comparing LincolnBurrows2017:fix-rate-limiter-bursting (3821069) with master (07fa576)²}

Footnotes

1. 23 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on master (54a5f83) during the generation of this report, so 07fa576 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[github-actions]

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