catalog-backend: switch default orphanStrategy to 'delete'

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

.changeset/loud-trains-take.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend': major
+---
+
+**BREAKING**: The default `catalog.orphanStrategy` has been switched to `'delete'`.

plugins/catalog-backend/config.d.ts

@@ -160,7 +160,7 @@ export interface Config {
     /**
      * The strategy to use for entities that are orphaned, i.e. no longer have
      * any other entities or providers referencing them. The default value is
-     * "keep".
+     * "delete".
      */
     orphanStrategy?: 'keep' | 'delete';
 

plugins/catalog-backend/src/processing/DefaultCatalogProcessingEngine.ts

@@ -344,7 +344,7 @@ export class DefaultCatalogProcessingEngine {
 
   private startOrphanCleanup(): () => void {
     const orphanStrategy =
-      this.config.getOptionalString('catalog.orphanStrategy') ?? 'keep';
+      this.config.getOptionalString('catalog.orphanStrategy') ?? 'delete';
     if (orphanStrategy !== 'delete') {
       return () => {};
     }