Repeat fix in #78387 for routes without params (#78568)
Depends on:
- https://github.com/vercel/vercel/pull/13275
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Follow up to #78387. When incremental PPR mode is enabled, we need to
create a special "inverse" route to handle tree requests for every route
in the manifest that doesn't have PPR enabled. #78387 fixed this for
"dynamic" routes — which in the context of the relevant module I believe
means routes with params, and has nothing to do with dynamic data in the
PPR sense — but it didn't handle for "static" routes — which here means
routes without any params.
The fix is to apply the same logic in #78387 for all routes, both
"static" and "dynamic", in the routes manifest.
