[3.13] gh-138584: Increase test coverage for `collections.UserList` (GH-138590) (#138611)

gh-138584: Increase test coverage for `collections.UserList` (GH-138590)

Some common tests in `test.list_tests.CommonTest` explicitly tested `list`
instead of testing the underlying list-like type defined in `type2test`.

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(cherry picked from commit d7b9ea5cab984497526fcc0b988e4eb5988c1e88)

Co-authored-by: dbXD320 <devanshbaghla320@gmail.com>
Co-authored-by: Devansh Baghla <devanshbaghla34@gmail.com>