delete only unnecessary reporter

Reporter that defines its own users at the time of this process are also loaded,
to avoid them from being deleted, to delete only the specified to unnecessary reporter.

railties/lib/rails/test_unit/minitest_plugin.rb

@@ -80,7 +80,8 @@ def self.plugin_rails_init(options)
       Minitest.backtrace_filter = ::Rails.backtrace_cleaner if ::Rails.respond_to?(:backtrace_cleaner)
     end
 
-    self.reporter.reporters.clear # Replace progress reporter for colors.
+    # Replace progress reporter for colors.
+    self.reporter.reporters.delete_if { |reporter| reporter.kind_of?(SummaryReporter) || reporter.kind_of?(ProgressReporter) }
     self.reporter << SuppressedSummaryReporter.new(options[:io], options)
     self.reporter << ::Rails::TestUnitReporter.new(options[:io], options)
   end