Update z_rubycheck.rake to no longer inject Xmx1g

This allows the environment variable JRUBY_OPTS to be used for setting properties like Xmx original pr: elastic#16420

Author: kaisecheng

rakelib/z_rubycheck.rake

@@ -29,7 +29,7 @@ if ENV['USE_RUBY'] != '1'
 
  # Ignore Environment JAVA_OPTS
  ENV["JAVA_OPTS"] = ""
- exec(jruby, "-J-Xmx1g", "-S", rake, *ARGV)
+ exec(jruby, "-S", rake, *ARGV)
  end
 end