Implements DO blockConcurrencyWhile test for Python Workers.

[dom96]

Just some tests to ensure we have coverage for blockConcurrencyWhile

Resolves EW-9784

[ask-bonk]

ResolveMessage: Cannot find module '@opencode-ai/plugin' from '/home/runner/work/workerd/workerd/.opencode/tools/bazel-deps.ts'

github run

[ask-bonk]

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[codspeed-hq]

Merging this PR will degrade performance by 21.08%

❌ 1 regressed benchmark
✅ 69 untouched benchmarks
⏩ 129 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	bodyWithHeaders[Response]	30.4 µs	38.5 µs	-21.08%

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_{Comparing dominik/do-block-concurrency-while-test (9f1a399) with main (ea98a22)}

Footnotes

1. 129 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. ↩