RouteNormalizerRequestSubscriber causes two extra route cache lookups

Problem/Motivation

RouteNormalizerRequestSubscriber runs before dynamic page cache, which runs before RoutePreloader. It needs the front/current route.

I'm wondering if it really needs to run this early. One problem is that it's specifically aims to detect cases that for dynamic page cache are actually the same thing. Such as being on the system path or alias, having index.php in the path or not. At least I think so, this needs investigation.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes