## Bug description

<img width="696" alt="Screen Shot 2021-09-16 at 2 37 41 PM" src="https://user-images.githubusercontent.com/13460330/133689529-c4fffc7f-53f8-494e-b7a8-7fb656fd50e6.png">

## Expected behavior

Bars and labels always show on top of axes and gridlines.

## How to reproduce

1. https://app.posthog.com/insights?insight=FUNNELS&properties=%5B%5D&filter_test_accounts=false&events=%5B%7B%22id%22%3A%22%24pageview%22%2C%22name%22%3A%22%24pageview%22%2C%22type%22%3A%22events%22%2C%22order%22%3A0%7D%2C%7B%22id%22%3A%22%24pageview%22%2C%22name%22%3A%22%24pageview%22%2C%22type%22%3A%22events%22%2C%22order%22%3A1%7D%2C%7B%22id%22%3A%22%24pageview%22%2C%22name%22%3A%22%24pageview%22%2C%22type%22%3A%22events%22%2C%22order%22%3A2%7D%5D&actions=%5B%5D&exclusions=%5B%5D&interval=day&funnel_from_step=0&funnel_to_step=1&new_entity=%5B%5D&funnel_viz_type=time_to_convert&display=FunnelViz

## Environment

- [X] PostHog Cloud
- [X] self-hosted PostHog (ClickHouse-based), version/commit: _please provide_
- [X] self-hosted PostHog (Postgres-based, legacy), version/commit: _please provide_

## Additional context



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

ee/clickhouse/queries/funnels/funnel_time_to_convert.py
steps_per_person_query = self.funnel_order.get_step_counts_query()
        self.params.update(self.funnel_order.params)
        
        
        from_step = self._filter.funnel_from_step or 0
        
        to_step = self._filter.funnel_to_step or len(self._filter.entities) - 1
        
        bin_count = self._filter.bin_count
        if bin_count is not None:
            
            if bin_count < 1:
                bin_count = 1
            elif bin_count > 90:
                bin_count = 90
            bin_count_identifier = str(bin_count)
            bin_count_expression = None
        else:
            
            bin_count_identifier = "bin_count"
            bin_count_expression = f"""
                count() AS sample_count,
                least(60, greatest(3, ceil(cbrt(sample_count)))) AS {bin_count_identifier},
            """
        if not (0 < to_step < len(self._filter.entities)):
            raise ValidationError(
                f'Filter parameter {FUNNEL_TO_STEP} can only be one of {", ".join(map(str, range(1, len(self._filter.entities))))} for time to convert!'
            )
        steps_average_conversion_time_identifiers = [
            f"step_{step+1}_average_conversion_time_inner" for step in range(from_step, to_step)