Add test case for parameter-mapping and remove the ruleHandler cache module

[zhangleispring]

Hi all:
      This PR is for Add test case for parameter-mapping plugin and remove 
ruleHandler cache module for plugins,
In my opinion, rulehandler cache module will be more general.
      If you have a good idea, we can exchange it here.
     PR: https://github.com/apache/incubator-shenyu/pull/1722
Thanks！