Can not display hadoop-st.png when using reverse proxy

using reverse proxy and applying APPLICATION_WEB_PROXY_BASE to change the base path, it can not find the hadoop-st.png.

(file: hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/webapp/view/HeaderBlock.java)

Issues:
1. Cannot display the image when you apply APPLICATION_WEB_PROXY_BASE=base_path/.
   The image path in the code is absolute path that leads to issue.
2. This should be converted to relative path /base_path/static/hadoop-st.png.