Add reproduction test for RetryLink AbortError with subscriptions

[Copilot]

Reproduction for AbortError: BodyStreamBuffer issue

Minimal reproduction test for #13125 (comment)

Issue

When RetryLink retries a subscription using AbortController, aborting the first attempt's controller triggers AbortError: BodyStreamBuffer was aborted which can interfere with the retry mechanism.

Test Added

Single test in src/link/retry/__tests__/retryLink.ts that:

• Uses HttpLink with mockMultipartSubscriptionStream for realistic multipart subscription behavior
• First attempt fails with protocol error (triggers retry and AbortController cleanup)
• Second attempt succeeds
• Verifies subscription completes successfully despite AbortController cleanup

The test documents the scenario and serves as a regression test.

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[apollo-cla]

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[changeset-bot]

⚠️ No Changeset found

Latest commit: e0fb81d

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[phryneas]

@copilot that's a lot, can this be condensed down?

[Copilot]

@copilot that's a lot, can this be condensed down?

Condensed to a single 40-line test in 415f9e9. Removed the extra test file and documentation.

[phryneas]

@copilot keep it more realistic with a HttpLink and a mockMultipartSubscriptionStream

[Copilot]

@copilot keep it more realistic with a HttpLink and a mockMultipartSubscriptionStream

Updated to use HttpLink with mockMultipartSubscriptionStream in e0fb81d. The test now demonstrates the realistic scenario with multipart subscription infrastructure and AbortController.

[jameswu1991]

related #13161