skip k6 api batch update when batch create fails

[rrennick]

Changes proposed in this Pull Request:

When running K6 tests I was seeing lots of the following error:

ERRO[0595] TypeError: Cannot read property '0' of undefined
Run    [at file:///Users/nobody/Sites/wc/wp-content/woocommerce/plugins/woocommerce/tests/performance/requests/api/orders.js:191:22(14)
	at go.k6.io/k6/js/modules/k6.(*K6).Group-fm (native)
	at ordersAPI (file:///Users/nobody/Sites/wc/wp-content/woocommerce/plugins/woocommerce/tests/performance/requests/api/orders.js:186:8(186))
	at allAPIFlow (file:///Users/nobody/Sites/wc/wp-content/woocommerce/plugins/woocommerce/tests/performance/tests/wc-baseline-load.js:329:1(4))

This PR adds a check to ensure that the batch add request returned a list of order IDs.

How to test the changes in this Pull Request:

Using the WooCommerce Testing Instructions Guide, include your detailed testing instructions:

1. In the plugins/woocommerce folder, run pnpm run env:dev --filter=woocommerce
2. Run pnpm run env:performance-init --filter=woocommerce
3. In the tests/performance folder, run k6 run tests/wc-baseline-load.js
4. Test suite should run successfully without logging the errors above.

[github-actions]

Hi , @woocommerce/solaris

Apart from reviewing the code changes, please make sure to review the testing instructions as well.

You can follow this guide to find out what good testing instructions should look like:
https://github.com/woocommerce/woocommerce/wiki/Writing-high-quality-testing-instructions

[github-actions]

Test Results Summary

Commit SHA: 36202d7

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	267	0	0	2	0	269	1m 2s
E2E Tests	189	0	0	10	0	199	17m 19s

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To view the full API test report, click here.
To view the full E2E test report, click here.
To view all test reports, visit the WooCommerce Test Reports Dashboard.

[nigeljamesstevenson]

Nice update - thanks @rrennick !