remove yarn.resourcemanager.hostname explicit set

I couldn't connect to the YARN UI on port 8088. I am not sure why it is specifically being set. Maybe i am missing something.

```
netstat -anp | grep 8088

tcp6       0      0 127.0.0.1:8088          :::*                    LISTEN      5378/java
```

After removing explicit set of yarn.resourcemanager.hostname I was able to access the YARN UI.

```
netstat -anp | grep 8088

tcp6       0      0 :::8088                 :::*                    LISTEN      8725/java
```