* This reverts commit 776d043.
* See #1586

> No one fix failure jobs over one month.

The CI failure was reported in
truffleruby/truffleruby#4094 and I did a lot
of work to replace Ripper with `Prism::Translation::Ripper` in
TruffleRuby and [improved `Prism::Translation::Ripper` to be compatible
enough](ruby/prism#3838).
There were only 6 days between report & fix.

It seems there was another failure after that, I found [this failing
run](https://github.com/ruby/rdoc/actions/runs/21367549712/job/61503325741)
```
/home/runner/work/rdoc/rdoc/lib/rdoc/parser/ripper_state_lex.rb:17:in 'Module#const_missing': uninitialized constant Prism::Translation::Ripper::Filter (NameError)
```

This has been fixed since then (`ruby -rripper -e 'p
Prism::Translation::Ripper::Filter'` works on truffleruby-head), given
the CI now passes.