BUG/MINOR: cache: Set conn-stream/channel EOI flags at the end of request

BUG/MINOR: cache: Set conn-stream/channel EOI flags at the end of request

This bug is the same than for the HTTP client. See "BUG/MINOR: httpclient:
Set conn-stream/channel EOI flags at the end of request" for details.

Note that because a filter is always attached to the stream when the cache
is used, there is no issue because there is no direct forwarding in this
case. Thus the stream analyzers are able to see the HTX_FL_EOM flag on the
HTX messge.

This patch must be backported as far as 2.0. But only CF_EOI must be set
because applets are not attached to a conn-stream on older versions.