Fixed #31624 -- Avoided subquery usage on QuerySet.all().delete().

Thanks Adam Johnson for the report.

Regression in 7acef095d7.

django/db/models/sql/compiler.py

@@ -1407,6 +1407,8 @@ class SQLInsertCompiler(SQLCompiler):
 class SQLDeleteCompiler(SQLCompiler):
     @cached_property
     def single_alias(self):
+        # Ensure base table is in aliases.
+        self.query.get_initial_alias()
         return sum(self.query.alias_refcount[t] > 0 for t in self.query.alias_map) == 1
 
     def _as_sql(self, query):