MEDIUM: http-rules: Enable the strict rewriting mode by default

MEDIUM: http-rules: Enable the strict rewriting mode by default

Now, by default, when a rule performing a rewrite on an HTTP message fails, an
internal error is triggered. Before, the failure was ignored. But most of users
are not aware of this behavior. And it does not happen very often because the
buffer reserve space in large enough. So it may be surprising. Returning an
internal error makes the rewrite failure explicit. If it is acceptable to
silently ignore it, the strict rewriting mode can be disabled.