omit random failure tests with FreeBSD

http://rubyci.s3.amazonaws.com/freebsd13/ruby-master/log/20220906T043002Z.fail.html.gz
  http://rubyci.s3.amazonaws.com/freebsd13/ruby-master/log/20220905T103002Z.fail.html.gz

test/drb/drbtest.rb

@@ -217,6 +217,7 @@ module DRbCore
   def test_06_timeout
     omit if RUBY_PLATFORM.include?("armv7l-linux")
     omit if RUBY_PLATFORM.include?("sparc-solaris2.10")
+    omit if RUBY_PLATFORM.include?("freebsd")
     omit if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # expecting a certain delay is difficult for --jit-wait CI
     Timeout.timeout(60) do
       ten = Onecky.new(10)

test/socket/test_socket.rb

@@ -562,6 +562,8 @@ class TestSocket < Test::Unit::TestCase
   end
 
   def test_closed_read
+    omit if RUBY_PLATFORM.include?("freebsd")
+
     require 'timeout'
     require 'socket'
     bug4390 = '[ruby-core:35203]'