fix launch_pyro.sh

## Type of Issue

https://github.com/facebookresearch/droidlet/blob/main/locobot/robot/launch_pyro.sh

A few issues
* $ip is read incorrectly
* maybe use a better alternative to xterm (xterm uses cut buffers and not the standard X11 clipboard selection by default)
* rviz doesn't show up on the remote computer when launch_pyro.sh is run through ssh

Select the type of issue:
- [x] Bug report (to report a bug)
- [x] Feature request (to request an additional feature)
- [ ] Tracker (I am just using this as a tracker)
- [ ] Refactor request
- [ ] Documentation Ask