Separate `BitXorOr` into `BitXor` and `BitOr` precedence (#16844)
## Summary
This change follows up on the bug-fix requested in #16747 --
`ruff_python_ast::OperatorPrecedence` had an enum variant, `BitXorOr`,
which which gave the same precedence to the `|` and `^` operators. This
goes against [Python's documentation for operator
precedence](https://docs.python.org/3/reference/expressions.html#operator-precedence),
so this PR changes the code so that it's correct.
This is part of the overall effort to unify redundant definitions of
`OperatorPrecedence` throughout the codebase (#16071)
## Test Plan
Because this is an internal change, I only ran existing tests to ensure
nothing was broken.
