Fix ElasticSearch ping InfoFacade endpoint

[jsharkey13]

This endpoint was not working because the cluster needs an authenticated request. It has been broken for a long time, but upgrading ES is a good reason to fix it.
Fix the tests to actually verify the expected behaviour, too; we always return a 200 OK, so they did not notice that the endpoint was broken.

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.95%. Comparing base (2da94f7) to head (ca48004).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...in/java/uk/ac/cam/cl/dtg/segue/api/InfoFacade.java	75.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #758   +/-   ##
=======================================
  Coverage   39.95%   39.95%           
=======================================
  Files         546      546           
  Lines       23886    23895    +9     
  Branches     2873     2873           
=======================================
+ Hits         9543     9547    +4     
- Misses      13435    13441    +6     
+ Partials      908      907    -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.