Review the text within the AdSense settings page when a site hasn't yet been reviewed / approved

## Bug Description

At present if an AdSense user uses Site Kit to add a new site to AdSense or adds a previously rejected site, the status within the Site Kit settings page will always display a "Your site is getting ready" or "You need to fix some things before we can connect Site Kit to your AdSense account" message respectively.

The second isn't really accurate, as their site is pending an AdSense review. Their site may be approved without any changes.

I have a [recording of this scenario here](https://recordit.co/x5pL8eot3m).


A relatively straightforward improvement here, is to change the text as per the below:

```diff
- You need to fix some things before we can connect Site Kit to your AdSense account.
+ Your site has not yet been approved for ads by the AdSense team.
```

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## Acceptance criteria

*

## Implementation Brief

* [ ]

### Test Coverage

*

## QA Brief

*

## Changelog entry

*

Start in the AdSense settings page by searching the codebase for the current “You need to fix some things before we can connect Site Kit to your AdSense account” text. Update the pending-review wording to match the issue and verify the settings page for a newly added or previously rejected site shows the approval message.

Written by the indexing model from the issue text.