* fix(azuresink): delete freshly created blob on write failure
appendBlobClient.Create() runs before content decryption and copy.
If MaybeDecryptContent or CopyFromChunkViews fails, an empty blob
is left behind, silently replacing any previous valid data. Add
cleanup that deletes the blob on content write errors when we were
the ones who created it.
* fix(azuresink): track recreated blobs for cleanup on write failure
handleExistingBlob deletes and recreates the blob when overwrite is
needed, but freshlyCreated was only set on the initial Create success
path. Set freshlyCreated = needsWrite after handleExistingBlob so
recreated blobs are also cleaned up on content write failure.
4fd974b16b