grpc_stats: removed runtime feature after deprecation period (#28144)

Commit Message: Removing
envoy.deprecated_features.grpc_stats_filter_enable_stats_for_all_methods_by_default which has been deprecated since 2021.

Additional Description:
Risk Level: low
Testing: existing unit tests
Docs Changes: docs update
Release Notes: added

Signed-off-by: Greg Greenway <ggreenway@apple.com>

Mirrored from https://github.com/envoyproxy/envoy @ 7e68d70d1ed3e1f12bc62e4487bb6b37ee25eb59

envoy/config/filter/http/grpc_stats/v2alpha/config.proto

@@ -46,9 +46,7 @@ message FilterConfig {
     //
     // .. attention::
     //   If neither `individual_method_stats_allowlist` nor `stats_for_all_methods` is set, the
-    //   behavior will default to `stats_for_all_methods=false`. This default value is changed due
+    //   behavior will default to `stats_for_all_methods=false`.
-    //   to the previous value being deprecated. This behavior can be changed with runtime override
-    //   `envoy.deprecated_features.grpc_stats_filter_enable_stats_for_all_methods_by_default`.
     google.protobuf.BoolValue stats_for_all_methods = 3;
   }
 }

envoy/extensions/filters/http/grpc_stats/v3/config.proto

@@ -48,9 +48,7 @@ message FilterConfig {
     //
     // .. attention::
     //   If neither ``individual_method_stats_allowlist`` nor ``stats_for_all_methods`` is set, the
-    //   behavior will default to ``stats_for_all_methods=false``. This default value is changed due
+    //   behavior will default to ``stats_for_all_methods=false``.
-    //   to the previous value being deprecated. This behavior can be changed with runtime override
-    //   ``envoy.deprecated_features.grpc_stats_filter_enable_stats_for_all_methods_by_default``.
     google.protobuf.BoolValue stats_for_all_methods = 3;
   }