Only filter post retrieval of entities for start nodes if working with entities that support start nodes. (#18287)

Author: AndyButland

src/Umbraco.Web.BackOffice/Controllers/EntityController.cs

@@ -895,6 +895,7 @@ public ActionResult<PagedResult<EntityBasic>> GetPagedChildren(
                     // Filtering out child nodes after getting a paged result is an active choice here, even though the pagination might get off.
                     // This has been the case with this functionality in Umbraco for a long time.
                     .Where(entity => ignoreUserStartNodes ||
+                                     (objectType == UmbracoObjectTypes.Document || objectType == UmbracoObjectTypes.Media) is false ||
                                      (ContentPermissions.IsInBranchOfStartNode(entity.Path, startNodeIds, startNodePaths, out var hasPathAccess) &&
                                      hasPathAccess))
                     .Select(source =>