Remove unused ObjC Starlark internal methods and clean up `apple_common.bzl`.

PiperOrigin-RevId: 822970923
Change-Id: Id971b1e30ceb930681dc2394e9f4bbb22af0d43b
diff --git a/cc/private/rules_impl/objc_compilation_support.bzl b/cc/private/rules_impl/objc_compilation_support.bzl
index 6a6e466..3bee1eb 100644
--- a/cc/private/rules_impl/objc_compilation_support.bzl
+++ b/cc/private/rules_impl/objc_compilation_support.bzl
@@ -1006,7 +1006,6 @@
 compilation_support = struct(
     register_compile_and_archive_actions = _register_compile_and_archive_actions,
     build_common_variables = _build_common_variables,
-    build_feature_configuration = _build_feature_configuration,
     get_library_for_linking = _get_library_for_linking,
     get_static_library_for_linking = _get_static_library_for_linking,
     validate_attributes = _validate_attributes,