## Bug description

There seems to be an issue with `get_available_timezones_with_offsets`, not sure at what point it broke.

```
Traceback (most recent call last):
    response = view_func(request, *args, **kwargs)
  File "/posthog/posthog/views.py", line 184, in preflight_check
    "available_timezones": get_available_timezones_with_offsets(),
    raise NonExistentTimeError(dt)
```

## Expected behavior
Preflight should work and the timezone list be returned correctly.


## How to reproduce

1. Just check `/_preflight` request

## Environment

- [X] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: _please provide_

## Additional context

Tagging @Twixes as you have more context on this.

#### *Thank you* for your bug report – we love squashing them!

posthog/utils.py
def __init__(self, klass):
        self.klass = klass
        self.instance = None
    def __call__(self, *args, **kwds):
        if self.instance == None:
            self.instance = self.klass(*args, **kwds)
        return self.instance
def get_machine_id() -> str:
    """A MAC address-dependent ID. Useful for PostHog instance analytics."""
    
    
    return hashlib.md5(uuid.getnode().to_bytes(6, "little")).hexdigest()
def get_table_size(table_name):
    from django.db import connection
    query = (
        f'SELECT pg_size_pretty(pg_total_relation_size(relid)) AS "size" '
        f"FROM pg_catalog.pg_statio_user_tables "
        f"WHERE relname = '{table_name}'"
    )
    cursor = connection.cursor()
    cursor.execute(query)
    return dict_from_cursor_fetchall(cursor)
def get_table_approx_count(table_name):