Part of #2460

When a merchant is setting up a new ads campaign from the plugin dashboard, they enter the "Set up paid campaign" flow, which includes individual steps for connecting a Google Ads account, configuring a campaign, and completing their billing setup.

In #2535, we are replacing the second step with the same component used during onboarding, which includes the ability to set up billing if needed. That makes the "Setup up billing" step redundant and can be removed.

Acceptance Criteria

• The "Setup up billing" step is no longer included in the AdsStepper.
• When billing is already set up, completing the "Create your paid campaign" step should result in the Setup Paid Ads flow being completed successfully with a new campaign.

Implementation Brief

The PR should get merged into the feature/2460-simplify-paid-ads-setup branch.

The AdsStepper component for the "Set up paid campaign" flow is in js/src/setup-ads/ads-stepper/index.js. The billing step can be removed from the array passed to the steps prop here.

The handleSubmit prop that is passed via formProps to the SetupBilling component will need to be moved to the component responsible for rendering the ads campaign setup (e.g. AdsCampaign) so that step can complete the form when finished.

For testing, billing status can be mocked using the following filter in an MU plugin:

function gla_filter_ads_billing_setup_status( $status ) {
	return 'approved';
}
add_filter( 'woocommerce_gla_ads_billing_setup_status', 'gla_filter_ads_billing_setup_status' );

Test Coverage

• Jest tests will be updated as a follow-up task at the completion of Remove the accounts connection page from the Ads Setup flow #2534, Consolidate the ad creation step in the Ads Setup flow with the one used in Onboarding #2535, and this issue.
• E2E tests related to the billing step can be removed from here.
  • Tests related to completion of the campaign should be retained as a standalone test. (current example)