Do not log bogus ERRORs when url_rewrite_access bypasses url_rewriter.

Do not log bogus ERRORs when url_rewrite_access bypasses url_rewriter.

The code uses HelperReply() object as a fake reply when url_rewrite_access
ACLs did not match. That fake reply had Unknown result code, which made Squid
log ERRORs to cache.log. We now use Error result code, just like
store_id_access does.

TODO: Bypass the overheads of creating and processing a fake reply by moving
all post-processing actions and checks into a new dedicated method and calling
that method when url_rewrite_access does not match. Do the same to the StoreID
code.