## Is your feature request related to a problem?

There's only 2 files where we use pandas, but pandas is 49MB and numpy is another 86MB, slowing down builds massively.

## Describe the solution you'd like

Replace pandas with a pure SQL/Python solution in
- posthog/queries/trends.py
- posthog/queries/sessions.py

Both of those have equivalent examples in Clickhouse (ee/clickhouse) that don't use Pandas.

## Describe alternatives you've considered

Continue using Pandas and clogging builds

## Additional context



#### *Thank you* for your feature request – we love each and every one!

posthog/queries/test/test_trends.py
person1 = person_factory(team_id=self.team.pk, distinct_ids=["person1"], properties={"name": "person1"})
            event_factory(
                team=self.team, event="watched movie", distinct_id="person1", timestamp="2020-01-01T12:00:00Z",
            )
            person2 = person_factory(team_id=self.team.pk, distinct_ids=["person2"], properties={"name": "person2"})
            event_factory(
                team=self.team, event="watched movie", distinct_id="person2", timestamp="2020-01-01T12:00:00Z",
            )
            event_factory(
                team=self.team, event="watched movie", distinct_id="person2", timestamp="2020-01-02T12:00:00Z",
            )
            
            event_factory(
                team=self.team, event="watched movie", distinct_id="person2", timestamp="2020-01-02T12:00:00Z",
            )
            person3 = person_factory(team_id=self.team.pk, distinct_ids=["person3"], properties={"name": "person3"})
            event_factory(