Remove attachment files from archive

[ietf-svn-bot]

owner:[email protected] type_cleanup | by [email protected]

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Attachments are now served directly from the message file. No need to store them as separate files.

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Issue migrated from trac:2647 at 2022-03-03 10:55:28 +0000

[ietf-svn-bot]

@[email protected] changed status from new to accepted