Prevent stores from calling helper API when local cache is not functioning

[thilinah]

All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Connected WooCommerce stores send requests to helper API for fetching details related to subscriptions and to get information about plugin updates. The responses from these API endpoints are cached to prevent stores from sending multiple requests frequently.

For example, the GET subscriptions request is cached for 1 hour and POST update-check request is cached for 12 hours.

But for some stores, the cache can be completely broken due to DB having a full disk. This is because when set_transient is called if the object cache is not configured for the site wp options table will be used to store the transient value. (further discussions in this P2 post and the issue)

Since the response from Helper API GET subscriptions and POST update-check is not the cached store will keep sending these requests. Basically this PR will block stores from calling above two endpoints if site local cache is not functioning.

Find more details on this P2 post.

Closes # .

• This PR is a very minor change/addition and does not require testing instructions (if checked you can ignore/remove the next section).

How to test the changes in this Pull Request:

• Have you followed the Writing high-quality testing instructions guide?

1. Make sure the site is connected to WCCOM via wp-admin/admin.php?page=wc-addons&section=helper
2. Add the following code into a mu-plugin to trick helper API client to think that the cache is broken.

add_filter( 'pre_transient__wc_helper_api_cache_test', function() {
	return 0;
} );

3. Run wp cache flush to remove any previously stored subscription response.
4. Visit My subscriptions page wp-admin/admin.php?page=wc-addons&section=helper
5. There should be an error mentioning Could not find any subscriptions on your WooCommerce.com account
   
6. Also there should be a log entry indicating the helper API request is skipped due to broken cache.
   
7. Same should happen when pressing Update button under My Subscriptions.
8. wp wc com extension list command should be blocked from making getting the subscription list.
9. Now remove the hook added in step 2 and notice that the update check and subscription requests are working fine.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you created a changelog file for each project being changed, ie pnpm --filter=<project> changelog add?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[codecov]

Codecov Report

Merging #36846 (4a624e2) into trunk (5b27b02) will increase coverage by 0.0%.
The diff coverage is 63.3%.

Additional details and impacted files

@@           Coverage Diff            @@
##             trunk   #36846   +/-   ##
========================================
  Coverage     46.7%    46.7%           
- Complexity   17164    17170    +6     
========================================
  Files          429      429           
  Lines        64734    64759   +25     
========================================
+ Hits         30203    30217   +14     
- Misses       34531    34542   +11     

Impacted Files	Coverage Δ
...ugins/woocommerce/includes/class-wc-post-types.php	2.9% <0.0%> (ø)
...oocommerce/includes/class-wc-regenerate-images.php	18.9% <0.0%> (ø)
...commerce/includes/admin/helper/class-wc-helper.php	7.7% <33.3%> (+0.1%)	⬆️
.../includes/admin/helper/class-wc-helper-updater.php	27.8% <44.4%> (+0.1%)	⬆️
.../woocommerce/includes/wc-conditional-functions.php	28.2% <85.7%> (+3.7%)	⬆️
...udes/admin/settings/class-wc-settings-accounts.php	97.5% <100.0%> (ø)
...lugins/woocommerce/includes/class-wc-countries.php	86.7% <100.0%> (ø)
...includes/emails/class-wc-email-cancelled-order.php	88.9% <100.0%> (ø)
...s/emails/class-wc-email-customer-on-hold-order.php	81.2% <100.0%> (ø)
...lugins/woocommerce/includes/wc-order-functions.php	76.3% <100.0%> (ø)
... and 7 more

[github-actions]

Test Results Summary

Commit SHA: 4a624e2

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	259	0	0	2	0	261	1m 11s
E2E Tests	189	0	0	6	0	195	18m 38s

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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.

[rcstr]

LGTM