revert: keep alpha entrypoint empty per maintainer guidance

Net-new package does not need alpha exports per awanlin's review.
Revert alpha.ts to export {}, remove default alias from module/index.ts,
and restore empty report-alpha.api.md.

Signed-off-by: pillaris <pillaris@adobe.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/catalog-backend-module-msgraph-incremental/report-alpha.api.md

@@ -3,11 +3,5 @@
 > Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
 
 ```ts
-import { BackendFeature } from '@backstage/backend-plugin-api';
-
-// @alpha (undocumented)
-const _feature: BackendFeature;
-export default _feature;
-
 // (No @packageDocumentation comment for this package)
 ```

plugins/catalog-backend-module-msgraph-incremental/src/alpha.ts

@@ -14,8 +14,4 @@
  * limitations under the License.
  */
 
-import { default as feature } from './module';
-
-/** @alpha */
-const _feature = feature;
-export default _feature;
+export {};

plugins/catalog-backend-module-msgraph-incremental/src/module/index.ts

@@ -15,7 +15,6 @@
  */
 
 export {
-  catalogModuleMicrosoftGraphIncrementalEntityProvider as default,
   catalogModuleMicrosoftGraphIncrementalEntityProvider,
   microsoftGraphIncrementalEntityProviderTransformExtensionPoint,
   type MicrosoftGraphIncrementalEntityProviderTransformsExtensionPoint,