fix: default relative canonical url should not contain search (#63843)
### What
Strip the search query for the `urlPathname` passed down to metadata
handling.
### Why
This is because the `urlPathname` from `staticGenerationStore` contains
query, so it will contain `?rsc` query for client navigation, which lead
to the relative path canonical url (e.g. `./`) will have the search
query along with it. This PR is to remove that and make sure always uses
pathname.
Reported by @pacocoursey
Closes NEXT-2963