core-app-api: route collection react-router stable compatibility

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/good-avocados-grow.md

@@ -0,0 +1,5 @@
+---
+'@backstage/core-app-api': minor
+---
+
+Updated the routing system to be compatible with `react-router` v6 stable.

packages/core-app-api/src/routing/collectors.test.tsx

@@ -109,7 +109,7 @@ function routeObj(
     routeRefs: new Set(refs),
     children: [
       {
-        path: '/*',
+        path: '*',
         caseSensitive: false,
         element: 'match-all',
         routeRefs: new Set(),

packages/core-app-api/src/routing/collectors.tsx

@@ -30,7 +30,7 @@ import { FeatureFlagged, FeatureFlaggedProps } from './FeatureFlagged';
 // mount points that are as deep in the routing tree as possible.
 export const MATCH_ALL_ROUTE: BackstageRouteObject = {
   caseSensitive: false,
-  path: '/*',
+  path: '*',
   element: 'match-all', // These elements aren't used, so we add in a bit of debug information
   routeRefs: new Set(),
 };