[IT Test] PublishPageValidationIT can't work reliably

The following IT test:

https://github.com/adobe/aem-project-archetype/blob/develop/src/main/archetype/it.tests/src/main/java/it/tests/PublishPageValidationIT.java

which checks all references on the published homepage can currently fail for two separate reasons:

- There is no publish. This should actually be handled by the underlying testing client, skipping the test if there is no publish available. Unfortunately it currently simply falls back to setting `localhost:4503` if no publish is set. This issue is tracked with CQ-4326829.

- The test (correctly) sometimes fails with :

``` PublishPageValidationIT.validateHomepage:82->verifyLinkedResources:108 Empty response body from [https://publish-p34468-e143152.adobeaemcloud.net/etc.clientlibs/tractorsupplycompanycloudservice/clientlibs/clientlib-dependencies.lc-d41d8cd98f00b204e9800998ecf8427e-lc.min.js]```

This happens when there are no clientlib dependencies defined yet, the link is still added to the output but returns 0 bytes.
Since this is expected behavior the test should e.g. issue a warning instead of failing. But it should also be investigated if it can prevented to render the link at all if there are no dependencies.

But until first point is fixed we have to disable the test, as it causes CM Pipelines to fail, which don't have a publish instance, e.g. Assets.