Remove files from chrony.d to avoid unmanaged configuration options.

Signed-off-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>

* Semi-automated using `ssf-formula` (v0.5.0)
* Fix errors shown below:

```bash
chrony-formula$ $(grep "\- yamllint" .travis.yml | sed -e "s:^\s\+-\s\(.*\):\1:")
pillar.example
  1:1       warning  missing document start "---"  (document-start)
  21:3      warning  comment not indented like content  (comments-indentation)
```

BREAKING CHANGE: `chrony.removed` replaced by `.clean` states.