Fix scrolling on navigation in app (#48863)

## What?

When investigating #48852 I found that when there's a `segmentPath` set
in the `focusAndScrollRef` it would compare that entire path with the
`segmentPath` of the layout-router. This logic works in cases where the
entire page is rendered but doesn't take into account cases where for
example a suspense boundary is triggered below the common layout.

Because of the order `useEffect` is run in we can already assume that if
a more specific match existed it would have scrolled there. As that is
not the case in e.g. #48852 it ended up opting out of scrolling
entirely. In order to fix that the logic needs to be different, it needs
to check if the layout-router's `segmentPath` matches, if it matches
every level then we can apply scrolling in that layout-router.

## How?

Implemented the opposite of the current logic, running `.every` on the
layout-router segmentPath instead of on the router provided segmentPath.

Fixes #48852
Fixes NEXT-1053

Related PR #48862

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packages/next/src/client/components/layout-router.tsx

@@ -140,20 +140,18 @@ interface ScrollAndFocusHandlerProps {
 class ScrollAndFocusHandler extends React.Component<ScrollAndFocusHandlerProps> {
   handlePotentialScroll = () => {
     // Handle scroll and focus, it's only applied once in the first useEffect that triggers that changed.
-    const { focusAndScrollRef } = this.props
+    const { focusAndScrollRef, segmentPath } = this.props
 
     if (focusAndScrollRef.apply) {
       // segmentPaths is an array of segment paths that should be scrolled to
       // if the current segment path is not in the array, the scroll is not applied
       // unless the array is empty, in which case the scroll is always applied
       if (
         focusAndScrollRef.segmentPaths.length !== 0 &&
-        !focusAndScrollRef.segmentPaths.some(
-          (segmentPath) =>
-            segmentPath.length === this.props.segmentPath.length &&
-            segmentPath.every((segment, index) =>
-              matchSegment(segment, this.props.segmentPath[index])
-            )
+        !focusAndScrollRef.segmentPaths.some((scrollRefSegmentPath) =>
+          segmentPath.every((segment, index) =>
+            matchSegment(segment, scrollRefSegmentPath[index])
+          )
         )
       ) {
         return

packages/next/src/client/components/router-reducer/reducers/navigate-reducer.ts

@@ -318,11 +318,14 @@ export function navigateReducer(
       currentTree = newTree
 
       for (const subSegment of generateSegmentsFromPatch(treePatch)) {
-        scrollableSegments.push(
-          [...flightSegmentPath, ...subSegment].filter(
-            (segment) => segment !== '__PAGE__'
-          )
-        )
+        const scrollableSegmentPath = [...flightSegmentPath, ...subSegment]
+        // Filter out the __DEFAULT__ paths as they shouldn't be scrolled to in this case.
+        if (
+          scrollableSegmentPath[scrollableSegmentPath.length - 1] !==
+          '__DEFAULT__'
+        ) {
+          scrollableSegments.push(scrollableSegmentPath)
+        }
       }
     }
   }