[3.12] gh-124498: Fix `TypeAliasType` not to be generic, when `type_params=()` (GH-124499) (#124604)

gh-124498: Fix `TypeAliasType` not to be generic, when `type_params=()` (GH-124499)
(cherry picked from commit abe5f799e6ce1d177f79554f1b84d348b6141045)

Co-authored-by: sobolevn <mail@sobolevn.me>