fetch: make readAllBytes "sync" #15824

Job	Run time
Lint	33s
Test with Node.js 20 compiled --without-intl	5m 4s
Test with Node.js 22 compiled --without-intl	5m 7s
dependency-review	14s
Test with Node.js 23 compiled --without-intl	5m 8s
Fuzzing	3m 27s
Test with SQLite enabled	36s
Test TypeScript types	37s
test (20, macos-latest) / Test with Node.js 20 on macos-latest	4m 44s
test (20, ubuntu-latest) / Test with Node.js 20 on ubuntu-latest	4m 16s
test (22, macos-latest) / Test with Node.js 22 on macos-latest	4m 8s
test (20, windows-latest) / Test with Node.js 20 on windows-latest	5m 52s
test (22, ubuntu-latest) / Test with Node.js 22 on ubuntu-latest	4m 51s
test (22, windows-latest) / Test with Node.js 22 on windows-latest	6m 17s
test (23, macos-latest) / Test with Node.js 23 on macos-latest	4m 18s
test (23, windows-latest) / Test with Node.js 23 on windows-latest	5m 41s
test (23, ubuntu-latest) / Test with Node.js 23 on ubuntu-latest	3m 58s
automerge	0s
	1h 4m 51s

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