## 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/utils.py
"default_event_name": "$pageview",
            "switched_team": getattr(request, "switched_team", None),
            **posthog_app_context,
        }
        if team_for_public_context:
            
            posthog_app_context["current_team"] = TeamPublicSerializer(
                team_for_public_context, context={"request": request}, many=False
            ).data
        elif request.user.pk:
            user = cast("User", request.user)
            user_permissions = UserPermissions(user=user, team=user.team)
            user_serialized = UserSerializer(
                request.user,
                context={"request": request, "user_permissions": user_permissions},
                many=False,
            )
            posthog_app_context["current_user"] = user_serialized.data
            posthog_distinct_id = user_serialized.data.get("distinct_id")
            if user.team:
                team_serialized = TeamSerializer(
                    user.team,
                    context={"request": request, "user_permissions": user_permissions},
                    many=False,
                )
                posthog_app_context["current_team"] = team_serialized.data
                posthog_app_context["frontend_apps"] = get_frontend_apps(user.team.pk)
                posthog_app_context["default_event_name"] = get_default_event_name(user.team)
    context["posthog_app_context"] = json.dumps(posthog_app_context, default=json_uuid_convert)
    if posthog_distinct_id: