Remove unecesary and harmful pend for TruffleRuby in TestRaiseNoBackt…

…raceException

* Specifically the second one causes `$HOME` to be unset, which breaks `File.expand_path('~')`.
* See ruby/irb#423

test/mri/tests/irb/test_raise_no_backtrace_exception.rb

@@ -4,7 +4,7 @@
 module TestIRB
   class TestRaiseNoBacktraceException < Test::Unit::TestCase
     def test_raise_exception
-      pend if RUBY_ENGINE == 'truffleruby'
+      # pend if RUBY_ENGINE == 'truffleruby' # https://github.com/ruby/irb/pull/423
       bundle_exec = ENV.key?('BUNDLE_GEMFILE') ? ['-rbundler/setup'] : []
       assert_in_out_err(bundle_exec + %w[-rirb -W0 -e IRB.start(__FILE__) -- -f --], <<-IRB, /Exception: foo/, [])
       e = Exception.new("foo")
@@ -23,7 +23,7 @@ def test_raise_exception_with_invalid_byte_sequence
     end
 
     def test_raise_exception_with_different_encoding_containing_invalid_byte_sequence
-      pend if RUBY_ENGINE == 'truffleruby'
+      # pend if RUBY_ENGINE == 'truffleruby' # https://github.com/ruby/irb/pull/423
       backup_home = ENV["HOME"]
       Dir.mktmpdir("test_irb_raise_no_backtrace_exception_#{$$}") do |tmpdir|
         ENV["HOME"] = tmpdir