Vale: Replace test fixture with test suite for each rule

The latest version (3.23) of vale lets you test each rule
using a test suite. A testsuite is a YAML file that includes
the input for the test. Use the following command to run
the test coverage for all the rules:

    vale --config=.vale-qdoc-test.ini --no-global test --coverage styles/Qt

You could also test a specific suite only by providing
the corresponding YAML file, which ends with the ".test.yml" name.

Change-Id: I68a3d760e65cdbc8abb4ddd10d32ea55ec817e03
Reviewed-by: Alexei Cazacov <alexei.cazacov@qt.io>