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/development/interpreters/ruby/patchsets.nix

@@ -1,29 +1,6 @@
 { patchSet, useRailsExpress, ops, patchLevel }:
 
 rec {
-  "2.0.0" = [
-    ./ssl_v3.patch
-    ./rand-egd.patch
-  ] ++ ops useRailsExpress [
-    "${patchSet}/patches/ruby/2.0.0/p${patchLevel}/railsexpress/01-zero-broken-tests.patch"
-    "${patchSet}/patches/ruby/2.0.0/p${patchLevel}/railsexpress/02-railsexpress-gc.patch"
-    "${patchSet}/patches/ruby/2.0.0/p${patchLevel}/railsexpress/03-display-more-detailed-stack-trace.patch"
-    "${patchSet}/patches/ruby/2.0.0/p${patchLevel}/railsexpress/04-show-full-backtrace-on-stack-overflow.patch"
-  ];
-  "2.1.10" = [
-    ./rand-egd.patch
-  ] ++ ops useRailsExpress [
-    # 2.1.10 patchsets are not available, but 2.1.8 patchsets apply
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/01-zero-broken-tests.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/02-improve-gc-stats.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/03-display-more-detailed-stack-trace.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/04-show-full-backtrace-on-stack-overflow.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/05-funny-falcon-stc-density.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/06-funny-falcon-stc-pool-allocation.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/07-aman-opt-aset-aref-str.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/08-funny-falcon-method-cache.patch"
-    "${patchSet}/patches/ruby/2.1.8/railsexpress/09-heap-dump-support.patch"
-  ];
   "2.2.9" = ops useRailsExpress [
     "${patchSet}/patches/ruby/2.2/head/railsexpress/01-zero-broken-tests.patch"
     "${patchSet}/patches/ruby/2.2/head/railsexpress/02-improve-gc-stats.patch"