Handle Apollo multipart failed-request inspection safely

[lbloder]

Context

The Apollo 4 and Apollo 5 integrations inspect HTTP response bodies to detect GraphQL errors. Multipart and incremental responses need separate handling so inspection does not buffer, block, or consume streaming bodies.

Scope

• Define safe failed-request inspection for multipart/incremental responses in sentry-apollo-4 and sentry-apollo-5.
• Preserve spans and breadcrumbs when body inspection is skipped or unsupported.
• Decide between skipping failed-request body inspection for multipart responses and parsing multipart parts for GraphQL errors.
• Add tests covering streaming behavior and body preservation.

WebSocket subscription instrumentation remains out of scope.

[linear-code]

JAVA-703

[adinauer]

We should treat this as a bug since adding Sentry to Apollo breaks the @defer and @stream features which use multipart responses. We considered adding an option to control whether to inspect multipart requests but decided against it since that means you're choosing at compile / release time whether to use or break the features. Broken defer/stream may mean the customers UI loads very slowly or worst case indefinitely.

We decided to no longer inspect the response body of multipart responses for errors.