Watchman uses wrong prefix for state directory

I get the following error when running `watchman get-sockname`:

```
> watchman get-sockname
2021-09-18T10:10:14,827: [] while computing sockname: failed to create /usr/local/var/run/watchman/k-state: Permission denied`
```

Even though Watchman has been installed with a different prefix (`/Users/k/homebrew`, NOT `/usr/local`)

```
> which watchman
/Users/k/homebrew/bin/watchman
```

This seems to be a recent issue because it used to work before. I'm not sure if issue is with Watchman or with its Homebrew formula.