## 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/lifecycle_query_runner.py
arrayConcat(arrayZip(all_activity, initial_status), arrayZip(dormant_periods, dormant_label)) as temp_concat,
                        arrayJoin(temp_concat) as period_status_pairs,
                        period_status_pairs.1 as start_of_period,
                        period_status_pairs.2 as status
                    FROM events
                    WHERE {event_filter}
                    GROUP BY person_id
                """,
                placeholders={
                    **self.query_date_range.to_placeholders(),
                    "event_filter": self.event_filter,
                    "trunc_timestamp": self.query_date_range.date_to_start_of_interval_hogql(
                        ast.Field(chain=["events", "timestamp"])
                    ),
                    "trunc_created_at": self.query_date_range.date_to_start_of_interval_hogql(
                        ast.Field(chain=["created_at"])
                    ),
                    "trunc_epoch": self.query_date_range.date_to_start_of_interval_hogql(
                        ast.Call(name="toDateTime", args=[ast.Constant(value="1970-01-01 00:00:00")])
                    ),
                },
                timings=self.timings,
            )
            sampling_factor = self.query.samplingFactor
            if sampling_factor is not None and isinstance(sampling_factor, float):
                sample_expr = ast.SampleExpr(sample_value=ast.RatioExpr(left=ast.Constant(value=sampling_factor)))
                events_query.select_from.sample = sample_expr
        return events_query
    @cached_property
    def periods_query(self):