fix: remove user_id filter when clearing default provider (enterprise only)

When setting a new default credential in enterprise mode, the code was
only clearing is_default for credentials matching the current user_id.
This caused issues when:
1. Enterprise credential A (synced with system user_id) was default
2. User sets local credential B as default
3. A still had is_default=true (different user_id)
4. Both A and B were considered defaults

The fix removes user_id from the filter only for enterprise deployments,
since enterprise credentials may have different user_id than local ones.
Non-enterprise behavior is unchanged to avoid breaking existing setups.

Fixes EE-1511

api/services/tools/builtin_tools_manage_service.py

@@ -417,9 +417,17 @@ class BuiltinToolManageService:
                 raise ValueError("provider not found")
 
             # clear default provider
-            session.query(BuiltinToolProvider).filter_by(
-                tenant_id=tenant_id, user_id=user_id, provider=provider, is_default=True
-            ).update({"is_default": False})
+            if dify_config.ENTERPRISE_ENABLED:
+                # Enterprise: clear ALL defaults for this provider in the tenant
+                # (regardless of user_id, since enterprise credentials may have different user_id)
+                session.query(BuiltinToolProvider).filter_by(
+                    tenant_id=tenant_id, provider=provider, is_default=True
+                ).update({"is_default": False})
+            else:
+                # Non-enterprise: only clear defaults for the current user
+                session.query(BuiltinToolProvider).filter_by(
+                    tenant_id=tenant_id, user_id=user_id, provider=provider, is_default=True
+                ).update({"is_default": False})
 
             # set new default provider
             target_provider.is_default = True