YARN-5848. Remove unnecessary public/crossdomain.xml from YARN UIv2 sub project. (Sunil G via wangda)

Change-Id: Ie295f88232192e6b520c335b0332383cc6a232c0

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-ui/public/crossdomain.xml

@@ -1,15 +0,0 @@
-<?xml version="1.0"?>
-<!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
-<cross-domain-policy>
-  <!-- Read this: www.adobe.com/devnet/articles/crossdomain_policy_file_spec.html -->
-
-  <!-- Most restrictive policy: -->
-  <site-control permitted-cross-domain-policies="none"/>
-
-  <!-- Least restrictive policy: -->
-  <!--
-  <site-control permitted-cross-domain-policies="all"/>
-  <allow-access-from domain="*" to-ports="*" secure="false"/>
-  <allow-http-request-headers-from domain="*" headers="*" secure="false"/>
-  -->
-</cross-domain-policy>