chore: deprecate REDUCE_DASHBOARD_BOOTSTRAP_PAYLOAD (#11244)

UPDATING.md

@@ -23,6 +23,8 @@ assists people when migrating to a new version.
 
 ## Next
 
+* [11244](https://github.com/apache/incubator-superset/pull/11244): The `REDUCE_DASHBOARD_BOOTSTRAP_PAYLOAD` feature flag has been removed after being set to True for multiple months.
+
 * [11172](https://github.com/apache/incubator-superset/pull/11172): Breaking change: SQL templating is turned off be default. To turn it on set `ENABLE_TEMPLATE_PROCESSING` to True on `DEFAULT_FEATURE_FLAGS`
 
 * [11155](https://github.com/apache/incubator-superset/pull/11155): The `FAB_UPDATE_PERMS` config parameter is no longer required as the Superset application correctly informs FAB under which context permissions should be updated.

superset/config.py

@@ -302,7 +302,6 @@ def _try_json_readsha(  # pylint: disable=unused-argument
     "PRESTO_EXPAND_DATA": False,
     # Exposes API endpoint to compute thumbnails
     "THUMBNAILS": False,
-    "REDUCE_DASHBOARD_BOOTSTRAP_PAYLOAD": True,
     "REMOVE_SLICE_LEVEL_LABEL_COLORS": False,
     "SHARE_QUERIES_VIA_KV_STORE": False,
     "SIP_38_VIZ_REARCHITECTURE": False,
@@ -628,11 +627,11 @@ class CeleryConfig:  # pylint: disable=too-few-public-methods
 # db configuration and a result of this function.
 
 # mypy doesn't catch that if case ensures list content being always str
-ALLOWED_USER_CSV_SCHEMA_FUNC: Callable[
-    ["Database", "models.User"], List[str]
-] = lambda database, user: [
-    UPLOADED_CSV_HIVE_NAMESPACE
-] if UPLOADED_CSV_HIVE_NAMESPACE else []
+ALLOWED_USER_CSV_SCHEMA_FUNC: Callable[["Database", "models.User"], List[str]] = (
+    lambda database, user: [UPLOADED_CSV_HIVE_NAMESPACE]
+    if UPLOADED_CSV_HIVE_NAMESPACE
+    else []
+)
 
 # Values that should be treated as nulls for the csv uploads.
 CSV_DEFAULT_NA_NAMES = list(STR_NA_VALUES)

superset/views/core.py

@@ -1626,8 +1626,6 @@ def dashboard(  # pylint: disable=too-many-locals
         # Filter out unneeded fields from the datasource payload
         datasources_payload = {
             datasource.uid: datasource.data_for_slices(slices)
-            if is_feature_enabled("REDUCE_DASHBOARD_BOOTSTRAP_PAYLOAD")
-            else datasource.data
             for datasource, slices in datasources.items()
         }