[`pylint`] Improve `repeated-equality-comparison` fix to use a `set` when all elements are hashable (`PLR1714`) (#16685)
## Summary
This PR promotes the fix improvements for `PLR1714` that were introduced
in https://github.com/astral-sh/ruff/pull/14372/ to stable.
The improvement is that the fix now proposes to use a set if all
elements are hashable:
```
foo == "bar" or foo == "baz" or foo == "qux"
```
Gets fixed to
```py
foo in {"bar", "baz", "qux"}
```
where it previously always got fixed to a tuple.
The new fix was first released in ruff 0.8.0 (Nov last year). This is
not a breaking change. The change was preview gated only to get some
extra test coverage.
There are no open issues or PRs related to this changed fix behavior.