Remove deprecated defaultPath migration helper from PageBlueprint

The `defaultPath` param was a compile-time migration artifact typed to
produce an error, guiding users to use `path` instead. The migration
period is over, so this removes it from the public API surface.

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

packages/app-example-plugin/report.api.md

@@ -87,7 +87,6 @@ const examplePlugin: OverridableFrontendPlugin<
         >;
       };
       params: {
-        defaultPath?: [Error: `Use the 'path' param instead`];
         path: string;
         title?: string;
         icon?: IconElement;

packages/frontend-plugin-api/report.api.md

@@ -1722,7 +1722,6 @@ export interface OverridableFrontendPlugin<
 export const PageBlueprint: ExtensionBlueprint_2<{
   kind: 'page';
   params: {
-    defaultPath?: [Error: `Use the 'path' param instead`];
     path: string;
     title?: string;
     icon?: IconElement;

packages/frontend-plugin-api/src/blueprints/PageBlueprint.tsx

@@ -59,10 +59,6 @@ export const PageBlueprint = createExtensionBlueprint({
   },
   *factory(
     params: {
-      /**
-       * @deprecated Use the `path` param instead.
-       */
-      defaultPath?: [Error: `Use the 'path' param instead`];
       path: string;
       title?: string;
       icon?: IconElement;