[autoscaler] Make commands `bash -i` to support newer bash (#4181)
[autoscaler] Make commands `bash -i` to support newer bash (#4181)

The generated command in autoscaler/updater.py throws non-zero exit status 127 on Ubuntu 18.04.

## Related issue number
Closes #4155, Closes #1444.

robertnishihara/ray,stephanie-wang/ray,stephanie-wang/ray,ray-project/ray,ujvl/ray-ng,robertnishihara/ray,pcmoritz/ray-1,robertnishihara/ray,ujvl/ray-ng,robertnishihara/ray,ray-project/ray,richardliaw/ray,atumanov/ray,pcmoritz/ray-1,pcmoritz/ray-1,pcmoritz/ray-1,robertnishihara/ray,robertnishihara/ray,stephanie-wang/ray,atumanov/ray,stephanie-wang/ray,ray-project/ray,atumanov/ray,richardliaw/ray,pcmoritz/ray-1,ray-project/ray,stephanie-wang/ray,richardliaw/ray,ray-project/ray,ray-project/ray,robertnishihara/ray,richardliaw/ray,richardliaw/ray,pcmoritz/ray-1,stephanie-wang/ray,atumanov/ray,atumanov/ray,ujvl/ray-ng,stephanie-wang/ray,ray-project/ray,pcmoritz/ray-1,stephanie-wang/ray,pcmoritz/ray-1,ujvl/ray-ng,atumanov/ray,richardliaw/ray,atumanov/ray,ray-project/ray,stephanie-wang/ray,robertnishihara/ray,richardliaw/ray,atumanov/ray,richardliaw/ray,robertnishihara/ray