ruby: remove unsupported versions (#34927)

* remove EOL ruby versions for security and maintenance reasons.
* only expose ruby_MAJOR_MINOR to the top-level. we don't provide
guarantees for the TINY version.
* mark all related packages as broken
* switch the default ruby version from 2.3.x to 2.4.x

pkgs/tools/video/flvtool2/default.nix

@@ -1,13 +1,14 @@
-{ buildRubyGem, lib, ruby_2_2 }:
+{ buildRubyGem, lib, ruby }:
 
 buildRubyGem rec {
-  ruby = ruby_2_2;
+  inherit ruby;
   name = "${gemName}-${version}";
   gemName = "flvtool2";
   version = "1.0.6";
   source.sha256 = "0xsla1061pi4ryh3jbvwsbs8qchprchbqjy7652g2g64v37i74qj";
 
   meta = {
+    broken = true; # depends on ruby 2.2
     homepage = https://github.com/unnu/flvtool2;
     description = "A tool to manipulate Macromedia Flash Video files";
     platforms = ruby.meta.platforms;