Revert "Fix #11003 TypeError: can only concatenate list (not "ImmutableLazyProxy(list)") to list"

This reverts commit 50fe12a5f515e3bb37ea0df7222b5c8c61229b63.
`ImmutableList`'s should also support `__radd__`. Fixes #11003.
Add test case which triggers #11003.
Merge pull request #11088 from s0undt3ch/hotfix/immutable-lists-sum

`ImmutableList`'s should also support `__radd__`