[ruby/irb] Silent the noise created when building Context in tests

ruby/irb@27e4274b3c

Author: st0012

test/irb/test_ruby_lex.rb

@@ -721,6 +721,7 @@ def build_context(local_variables = nil)
         end
       end
 
+      IRB.conf[:VERBOSE] = false
       IRB::Context.new(nil, workspace)
     end
   end