srun: error: Unable to allocate resources: Unable to contact slurm controller (connect failure)

Template: [Slurm](https://github.com/Azure/azure-quickstart-templates/tree/master/slurm)
### Issue Details

Upon restarting a VM, slurm seems to break down. How might it be possible to prevent this?
### Repro steps
1. Use the button to launch a slurm cluster.
2. ssh into master
3. `srun -N3 hostname` -> succeeds
4. Restart master
5. ssh into master
6. `srun -N3 hostname` -> fails with error message:

```
srun: error: Unable to allocate resources: Unable to contact slurm controller (connect failure)
```

Start with the Slurm template linked in the issue and inspect how the master VM configures or starts the Slurm controller after boot. Reproduce the sequence by running `srun -N3 hostname`, restarting the master, and running it again; done means the command succeeds after the restart without manual recovery.

Written by the indexing model from the issue text.