backend-test-utils: avoid cleanup if no databases are supported

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

.changeset/pretty-ghosts-scream.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': patch
+---
+
+`TestDatabases.create` will no longer set up an `afterAll` test handler if no databases are supported.

packages/backend-test-utils/src/database/TestDatabases.ts

@@ -91,9 +91,11 @@ export class TestDatabases {
 
     const databases = new TestDatabases(supportedIds);
 
-    afterAll(async () => {
-      await databases.shutdown();
-    });
+    if (supportedIds.length > 0) {
+      afterAll(async () => {
+        await databases.shutdown();
+      });
+    }
 
     return databases;
   }