add mdm configured endpoints for DDM assets for testing (#49633)

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**Related issue:** Resolves #

Saw I missed these when doing the DDM assets backend

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

## Testing

- [x] Added/updated automated tests
- [ ] QA'd all new/changed functionality manually


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## Summary by CodeRabbit

* **Tests**
* Expanded endpoint coverage for device management asset routes,
including listing, retrieving, deleting, and batch creation.
  * Documented a remaining limitation affecting multipart asset uploads.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

server/service/testing_utils_test.go

@@ -910,6 +910,12 @@ func mdmConfigurationRequiredEndpoints() []struct {
 		{"POST", "/api/fleet/orbit/setup_experience/status", false, true},
 		{"POST", "/api/latest/fleet/software/web_apps", false, true},
 		{"POST", "/api/latest/fleet/hosts/1/name_template/resend", false, true},
+		{"GET", "/api/latest/fleet/assets", false, true},
+		{"GET", "/api/latest/fleet/assets/1", false, true},
+		// TODO: multipart/form data parsing issue, see comment above
+		// {"POST", "/api/latest/fleet/assets", false, true},
+		{"DELETE", "/api/latest/fleet/assets/1", false, true},
+		{"POST", "/api/latest/fleet/assets/batch", false, true},
 	}
 }