Use route path instead of url in metric labels

[YvesPasteur]

The previous method to deal with the Url doesn't handle very good routes like /foo/123/bar where foo and bar are resource names and 123 is a changing id.

We change to use the routes as defined in the routers with placeholders, ex : '/foo/{id}/bar'

[galbacarys]

Can this please be merged in? This would fix the issue I'm having as well.

@roylines