Container sync no longer sending swift_bytes value

Container sync had a bug where it'd send out the trailing
"; swift_bytes=xxx" part of the content-type header. That trailing part
is just for internal cluster usage by SLO. Since that needed to be
stripped in two places now, I separated it out to a function that both
spots call.

Change-Id: Ibd6035d7a6b78205344bcc9d98bc1b7a9d463427
Merge "Container sync no longer sending swift_bytes value"