harden lazy wheel wheel error handling

[abn]

This change attempts to provide a catch-all safety net for circumstances where an index server is behaving badly when ranged requests are made.

Additionally, this change also helps guard against missing "Content-Range" headers in specific scenarios.

Resolves: #9042
Mitigtates: #9056

[aabmets]

Great job! Thank you a lot for fixing this! :)

[dimbleby]

#9056 looks as though it provides another instance of the LazyWheel code making optimistic assertions about server behaviour, dunno whether it makes sense to handle that in this pull request or separately

526│ assert response_length == min(initial_chunk_size, ret_length)

[abn]

dunno whether it makes sense to handle that in this pull request or separately

I reckon another PR might be better largely because I do not want to hold this up too long since this will in-effect solve that as well, or make it not impact UX. But might be good to have a targeted fix for defense-in-depth measure.

[github-actions]

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