Revert force_activate feature. It's unnecessary for Ruby 3.4.

I will add this feature for Ruby 3.5 again.

prelude.rb

@@ -1,49 +1,12 @@
 class Binding
   # :nodoc:
   def irb
-    begin
+    require 'irb'
-      require 'irb'
-    rescue LoadError, Gem::LoadError
-      force_activate 'irb'
-      retry
-    end
     irb
   end
 
   # suppress redefinition warning
   alias irb irb # :nodoc:
-
-  private def force_activate(gem)
-    Bundler.reset!
-
-    builder = Bundler::Dsl.new
-    if Bundler.definition.gemfiles.empty? # bundler/inline
-      Bundler.definition.locked_gems.specs.each{|spec| builder.gem spec.name, spec.version.to_s }
-    else
-      Bundler.definition.gemfiles.each{|gemfile| builder.eval_gemfile(gemfile) }
-    end
-    builder.gem gem
-
-    definition = builder.to_definition(nil, true)
-    definition.validate_runtime!
-
-    begin
-      orig_ui = Bundler.ui
-      orig_no_lock = Bundler::Definition.no_lock
-
-      ui = Bundler::UI::Shell.new
-      ui.level = "silent"
-      Bundler.ui = ui
-      Bundler::Definition.no_lock = true
-
-      Bundler::Runtime.new(nil, definition).setup
-    rescue Bundler::GemNotFound
-      warn "Failed to activate #{gem}, please install it with 'gem install #{gem}'"
-    ensure
-      Bundler.ui = orig_ui
-      Bundler::Definition.no_lock = orig_no_lock
-    end
-  end
 end
 
 module Kernel