[WEBUI] Remove debug feature for vis.js

`vis.min.js` refers `vis.map` and this even refers `vis.js` which is used for debug `vis.js` but this debug feature is not needed for Spark itself.

This issue is really minor so I don't file this in JIRA.

/CC andrewor14

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #5994 from sarutak/remove-debug-feature-for-vis and squashes the following commits:

8be038f [Kousuke Saruta] Remove vis.map entry from .rat-exclude
7404945 [Kousuke Saruta] Removed debug feature for vis.js

.rat-excludes

@@ -36,7 +36,6 @@ graphlib-dot.min.js
 sorttable.js
 vis.min.js
 vis.min.css
-vis.map
 .*avsc
 .*txt
 .*json