Fixes #28018: API tests in yaml files do not really support text content

[clarktsiory]

https://issues.rudder.io/issues/28018

The parsing of the YAML always assumed JSON content, even with type: text. It was simply missing taking the type into account for parsing and cleaning, in which case the text should be stripped.

There are only a few tests making use of type: text, in the Openscap plugin

[clarktsiory]

Commit modified

[clarktsiory]

Commit modified

[Normation-Quality-Assistant]

OK, merging this PR