revert(salt): avoid FreeBSD master boxes (unused in the formula)

This reverts commit cbaf92f.

Reverting since this isn't done with the docker containers in
`kitchen.yml` and so becomes extra code (and conditional) for no
practical use.

ssf/files/default/kitchen.vagrant.yml

@@ -28,9 +28,6 @@ platforms:
            (os == 'openbsd' and not testing_openbsd.active) or
            (os == 'windows' and not testing_windows.active) %}
   {%-     continue %}
-  {#-   Avoid `master` boxes for the `salt-formula` #}
-  {%-   elif [semrel_formula, salt_ver] == ['salt', 'master'] %}
-  {%-     continue %}
   {%-   endif %}
   - name: {{ os | replace('/', '-') }}-{{ os_ver | replace('.', '') }}-{{ salt_ver | replace('.', '-') }}-py{{ py_ver }}
     driver: