[ty] Add some missing calls to normalized_impl (#19074)

## Summary

I hoped this might fix the latest stack overflows on
https://github.com/astral-sh/ruff/pull/18659... it doesn't look like it
does, but these changes seem like they're probably correct anyway...?

## Test Plan

<!-- How was it tested? -->

crates/ty_python_semantic/src/types/generics.rs

@@ -385,7 +385,8 @@ impl<'db> Specialization<'db> {
         let tuple_inner = self
             .tuple_inner(db)
             .and_then(|tuple| tuple.normalized_impl(db, visitor));
-        Self::new(db, self.generic_context(db), types, tuple_inner)
+        let context = self.generic_context(db).normalized_impl(db, visitor);
+        Self::new(db, context, types, tuple_inner)
     }
 
     pub(super) fn materialize(self, db: &'db dyn Db, variance: TypeVarVariance) -> Self {

crates/ty_python_semantic/src/types/tuple.rs

@@ -654,7 +654,8 @@ impl<'db> VariableLengthTuple<Type<'db>> {
             .prenormalized_suffix_elements(db, None)
             .map(|ty| ty.normalized_impl(db, visitor))
             .collect::<Vec<_>>();
-        Self::mixed(prefix, self.variable.normalized(db), suffix)
+        let variable = self.variable.normalized_impl(db, visitor);
+        Self::mixed(prefix, variable, suffix)
     }
 
     fn materialize(&self, db: &'db dyn Db, variance: TypeVarVariance) -> TupleSpec<'db> {