Revert "Workaround for Style/RedundantBegin when using JRuby 9.2"

## Summary

Revert 1533ece

Current RuboCop (1.52) requires Ruby 2.7+ and JRuby 9.4+.
So JRuby 9.2 has been dropped from runtime version.

## Additional Information

jruby/jruby#6642 has been resolved in JRuby 9.4:

```ruby
# example.rb
require 'ripper'

class RipperParser < Ripper
  def on_parse_error(message)
    raise message
  end
end

RipperParser.new(<<~RUBY).parse
  foo do
    bar do
  end
rescue NameError
  converted << nil
end
RUBY
```

```console
$ ruby -v
jruby 9.4.2.0 (3.1.0) 2023-03-08 90d2913fda Java HotSpot(TM) 64-Bit Server VM 25.271-b09 on 1.8.0_271-b09 +jit [x86_64-darwin]
$ ruby example.rb # No errors
```

lib/rubocop/cop/lint/shadowed_exception.rb

@@ -121,18 +121,12 @@ def evaluate_exceptions(group)
 
           if rescued_exceptions.any?
             rescued_exceptions.each_with_object([]) do |exception, converted|
-              # FIXME: Workaround `rubocop:disable` comment for JRuby.
-              #        https://github.com/jruby/jruby/issues/6642
-              # rubocop:disable Style/RedundantBegin
-              begin
-                RuboCop::Util.silence_warnings do
-                  # Avoid printing deprecation warnings about constants
-                  converted << Kernel.const_get(exception.source)
-                end
-              rescue NameError
-                converted << nil
+              RuboCop::Util.silence_warnings do
+                # Avoid printing deprecation warnings about constants
+                converted << Kernel.const_get(exception.source)
               end
-              # rubocop:enable Style/RedundantBegin
+            rescue NameError
+              converted << nil
             end
           else
             # treat an empty `rescue` as `rescue StandardError`