[CCR] Remote clusters API integration test failure

[cjcenizal]

As discovered in #27608 (comment), the Remote Clusters List API integration test fails on CI. There are two things odd about this:

1. This test didn't fail originally, so why is it failing now? Possibly this recent ES change relating to address-resolution in remote/info has something to do this it: https://github.com/elastic/elasticsearch/pull/36671/files#diff-d390b91a2cae82a4f90f1386f8428695R679

2. @joshdover Tried running this test locally and it failed but with a different assertion mismatch. Why are we getting non-deterministic responses back in different environments?

Are these tests operating against actual running clusters? Or are they operating against some sort of mocked clusters? If the former, then I think this partially explains why this test is unreliable. When they were originally written, we probably had a remote cluster running on our machines, so we were making assertions against an environment which differs from the one when the tests are run by CI.

I still don't understand how they were passing in the first place, though. There must have been a cluster running locally on the CI environment, perhaps created by another set of tests?

[elasticmachine]

Pinging @elastic/es-ui

[joshdover]

FYI this test was disabled in master, 6.x, and 6.6 branches.

[joshdover]

@sebelga Were you able to see the same failures I was seeing? In particular I was seeing 0 connected nodes and isConnected: false in the response when running on my machine.

[sebelga]

@joshdover Not sure what exactly happened on ES side but I updated the seed host in the test and everything is back like it was before. I put you as a reviewer for #27778 but also @jen-huang in case you're on holidays 😊

[jen-huang]

I believe this can be closed now since the fix (#27778) is merged.