WordPress 6.7 Compatibility: Fix the issue that E2E test can't log in to wp-admin

[eason9487]

Changes proposed in this Pull Request:

With WordPress 6.7-RC3, the E2E test failed to start due to match two elements when trying to click the "Log In" button.

Trying to log-in as admin...
Admin log-in failed, Retrying... 0/5
locator.click: Error: strict mode violation: locator('text=Log In') resolved to 2 elements:
    1) <h1 class="screen-reader-text">Log In</h1> aka getByRole('heading', { name: 'Log In' })
    2) <input type="submit" id="wp-submit" value="Log In" name="wp-submit" class="button button-primary button-large"/> aka getByRole('button', { name: 'Log In' })

This PR ensures that it can locate the "Log In" button.

Checks:

• Does your code follow the WordPress coding standards?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Detailed test instructions:

View the successful run: https://github.com/woocommerce/woocommerce-google-analytics-integration/actions/runs/11792649422/job/32846651874

Changelog entry

Dev - WordPress 6.7 Compatibility: Fix the issue that E2E test can't log in to wp-admin.

[eason9487]

I will be skipping code review for this PR as it's a developer-facing only change and a similar fix has been reviewed and approved.