[api][conf] Refactor API tests and configuration handling (#4181)

- Enhanced the configuration retrieval in the API to include new flags for sharing and usage collection. This fixes bug of hue_config present ClusterConfig getting overridden.
- Removed redundant configuration entries from the ClusterConfig model.
- Reorganized import statements for consistency and clarity.
- Updated test cases to check for all config fields, improve readability and maintainability, including adjustments to JSON handling and assertions.

Author: Harshg999

desktop/core/src/desktop/api2.py

@@ -41,6 +41,7 @@
 from desktop import appmanager
 from desktop.auth.backend import is_admin
 from desktop.conf import (
+  COLLECT_USAGE,
   CUSTOM,
   ENABLE_CHUNKED_FILE_UPLOADER,
   ENABLE_CONNECTORS,
@@ -148,6 +149,8 @@ def get_config(request):
     'enable_task_server': TASK_SERVER_V2.ENABLED.get(),
     'enable_workflow_creation_action': ENABLE_WORKFLOW_CREATION_ACTION.get(),
     'allow_sample_data_from_views': ALLOW_SAMPLE_DATA_FROM_VIEWS.get(),
+    'enable_sharing': ENABLE_SHARING.get(),
+    'collect_usage': COLLECT_USAGE.get(),
   }
 
   # Storage browser configuration