Duplicate dates on x-axis in All Traffic and Search traffic widgets on dashboard

## Bug Description

While testing #6034 I noticed a UX/UI issue, when in gathering state, and 7 days is selected as the data range.

The dates on the x-axis are duplicated on the all traffic and search traffic widgets.

I initially thought it was a regression from the ticket I was testing but the issue occurs on the latest version of Site Kit.

This is an issue on the main, entity and view only dashboard.

Update: Just adding that the issue is also appearing on 14 days for the all traffic widget. It's fine for search traffic chart.



## Steps to reproduce

1. Set up a new Site Kit with Analytics.
2. Ensure that it is in gathering data state. (which it should be for a new site)
3. Go to the dashboard and observe the duplicate dates in the widgets.

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## Acceptance criteria

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## Implementation Brief

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### Test Coverage

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## QA Brief

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## Changelog entry

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Start by reproducing the issue on a new Site Kit setup with Analytics in the gathering-data state, using the dashboard's 7-day range and then the 14-day range for All Traffic. Inspect the date-label rendering for the All Traffic and Search traffic widgets across the main, entity, and view-only dashboards; done means the affected x-axes show each date only once.

Written by the indexing model from the issue text.