Remove mention of broken YAML subdocument profile negation

[shakuzen]

Documenting this feature misleads users into thinking it should work. The documentation can be added back once gh-8011 is fixed.

[snicoll]

@shakuzen I think I lost you as why that section of the doc is linked to #8011

[shakuzen]

The removed section of the doc is the only description of negated profiles. Negated profiles are what is reported as not working in #8011 (with repro project and test linked in the issue description). I'm not sure if negated profiles ever worked. The unit tests for SpringProfileDocumentMatcher pass but I haven't been able to actually get negated profiles to work as described in any project or integration test.

[wilkinsona]

Support for profile negation was introduced in 1.4. That would suggest one of the following:

1. It's really broken and no one's using it.
2. It largely works other than the problem described in SpringProfileDocumentMatcher does not work as expected #8011.

I think that 2 is the more likely, particularly as it was a contribution and, presumably, it works for @mbenson's original use case at least. Rather than just removing the documentation I'd prefer to either fix #8011 or to remove the functionality altogether.

[mbenson]

I'm still ready to participate in a solution for #8011. Recall that I had some code working there last year that hopefully would at least be a starting point.

[wilkinsona]

We've agreed that just removing the documentation isn't the right approach. We'll try to get to #8011 before 2.0 GAs.