[rubygems/rubygems] Remove unused method

https://github.com/rubygems/rubygems/commit/b1b39b8c06

lib/bundler/installer.rb

@@ -202,8 +202,6 @@ module Bundler
         return jobs
       end
 
-      return 1 unless can_install_in_parallel?
-
       Bundler.settings[:jobs] || processor_count
     end
 
@@ -263,10 +261,6 @@ module Bundler
       end
     end
 
-    def can_install_in_parallel?
-      true
-    end
-
     def install_in_parallel(size, standalone, force = false)
       spec_installations = ParallelInstaller.call(self, @definition.specs, size, standalone, force)
       spec_installations.each do |installation|