Bug 1827703

Cause: A previous change to radosgw chunk handling broke certain older clients which were incorrectly setting both transfer-encoding: chunked and content-length. Consequence: Those older clients would no longer work. Worse yet, they could leave the connection in an inconsistent state, which if a proxy server was involved, could also result in occasional random transient failures seen by unrelated clients. Fix: Additional switchable logic has been added to emulate the orignal behavior. The switch to turn this off has been named "enable_unsafe_request_smuggling" to denote its undesirable security properties. It defaults to enabled in this version, but will default to disabled in the next major release. There is also separate logic to close connections that become inconsistent, which will always be eanbled. Result: Legacy clients should again work, and there should no longer be any weird traisent failures in unrelated clients.