CLEANUP: http: rename the misleading http_check_access_rule

CLEANUP: http: rename the misleading http_check_access_rule

Several bugs were introduced recently due to a misunderstanding of how
this function works and what it was supposed to do. Since it's supposed
to only return the pointer to a rule which aborts further processing of
the request, let's rename it to avoid further issues.

The function was also slightly cleaned up without any functional change.