[dashboard] teleop commands are inconsistently executed

## Type of Issue

Noticing that the 1 teleop command on the locobot agent can get executed 3-6 times. Is this some quirk of the dashboard [key handler](https://github.com/facebookresearch/droidlet/blob/main/dldashboard/web/src/StateManager.js#L166)? I tried a quick hack of setting the commands array to empty [ after they are emitted ](https://github.com/facebookresearch/droidlet/blob/main/dldashboard/web/src/StateManager.js#L207) but that didn't fix this.

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

## Expected Behavior

Each teleop command only gets executed once.

## Steps to reproduce

Play with the teleop commands on the locobot agent. I encountered this while playing with physical locobot.