## Bug description

The grouped-by-month view in charts is hella confusing. The x-axis shows a date that does not reflect the value on the y-axis.

1. the y-axis shows the number for the END of the month
2. the x-axis reads as "beginning of the month"

![CleanShot 2024-02-05 at 10 23 30@2x](https://github.com/PostHog/posthog/assets/35429197/d78df745-8319-4b78-95fa-d96f18aee357)

### Comparison with daily grouping

Compare the "group by month" view with "group by day". The x-axis labeling aligns with the y-axis values. 

![CleanShot 2024-02-05 at 10 29 20@2x](https://github.com/PostHog/posthog/assets/35429197/998825fa-7406-4214-8310-8f173980f80c)


## How to reproduce

1. Group a chart by month 
2. select "unique events"

## Proposal 

### 1. easy fix - remove the "1." from the labelling

- will still confuse readers with "is this the beginning or end of the month"

![CleanShot 2024-02-05 at 10 23 30@2x](https://github.com/PostHog/posthog/assets/35429197/1a0ae6d4-0e02-4b32-86ab-7b0e069655ed)

### 2. correct fix - show end of month

- removes ambiguity from "is that the beginning or end of month"
- harder to implement because months have different end days

![CleanShot 2024-02-05 at 10 23 30@2x](https://github.com/PostHog/posthog/assets/35429197/61226346-7f97-4bcd-87bf-53fc83c75245)


cc @jannesblobel
posthog/hogql_queries/insights/trends/trends_query_runner.py
"properties": {},
                    },
                }
            
            if self.query.trendsFilter is not None and self.query.trendsFilter.compare:
                labels = [
                    "{} {}".format(
                        self.query.interval if self.query.interval is not None else "day",
                        i,
                    )
                    for i in range(len(series_object.get("labels", [])))
                ]
                series_object["compare"] = True
                series_object["compare_label"] = "previous" if series.is_previous_period_series else "current"
                series_object["labels"] = labels
            
            if self.query.breakdownFilter is not None and self.query.breakdownFilter.breakdown is not None:
                remapped_label = None
                if self._is_breakdown_field_boolean():
                    remapped_label = self._convert_boolean(get_value("breakdown_value", val))
                    if remapped_label == "" or remapped_label is None:
                        
                        if series_object["count"] == 0 and series_object.get("aggregated_value", 0) == 0:
                            continue
                        remapped_label = "none"
                    series_object["label"] = "{} - {}".format(series_object["label"], remapped_label)
                    series_object["breakdown_value"] = remapped_label
                elif self.query.breakdownFilter.breakdown_type == "cohort":
                    cohort_id = get_value("breakdown_value", val)
                    cohort_name = "all users" if str(cohort_id) == "0" else Cohort.objects.get(pk=cohort_id).name