restart_habitat crashes

## Type of Issue

The util to restart habitat ([here](https://github.com/facebookresearch/droidlet/blob/main/droidlet/lowlevel/locobot/remote/remote_locobot.py#L70)) crashes with the following stack trace when called after a habitat env has already been created. The API works the first time only.

```
I0901 13:31:22.345513 160 Simulator.cpp:64] Loading navmesh from /Replica-Dataset/apartment_0/habitat/mesh_semantic.navmesh
I0901 13:31:22.345731 160 Simulator.cpp:66] Loaded.
I0901 13:31:22.345765 160 SceneGraph.h:92] Created DrawableGroup:
I0901 13:31:22.346117 160 WindowlessContext.cpp:100] [EGL] Detected 3 EGL devices
I0901 13:31:22.346282 160 WindowlessContext.cpp:121] [EGL] Selected EGL device 0 for CUDA device 0
I0901 13:31:22.346333 160 WindowlessContext.cpp:135] [EGL] Version: 1.5
I0901 13:31:22.346345 160 WindowlessContext.cpp:136] [EGL] Vendor: NVIDIA
GL::Context: Another context currently active
```

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## Expected Behavior

Restart the habitat environment

## Steps to reproduce

Call the API twice.