test(pillar): use static test/salt/pillar/top.sls

The kitchen-salt provisionner have the `pillars_from_directories`
option to recusively copy directories under target pillar root.

This has 3 advantages:

- simplify `kitchen.yml`

- manage pillar assignment with standard salt targetting mechanism,
  this avoid the dedicated `gentoo` suite (it could have been done
  from `kitchen.yml` itself by the way)

- ease the test outside kitchen by running `salt-call` directly with
  `--pillar-root` like:
  ```
  salt-call --local --id test-minion.example.net \
    --file-root=template-formula/ \
    --pillar-root=template-formula/test/salt/pillar/ \
    state.show_sls TEMPLATE
  ```

* test/salt/pillar/top.sls: limit `gentoo` pillars based on `os_family`
  grain.

* kitchen.yml (suites): remove the now useless `gentoo` suite.
  Define an empty required `pillars` to not override static `top.sls`.
  Define `pillars_from_directories` to copy them under `pillar_root`.

kitchen.yml

@@ -429,64 +429,17 @@ verifier:
 
 suites:
   - name: default
-    excludes:
-      - gentoo-stage3-latest-master-py3
-      - gentoo-stage3-systemd-master-py3
-      - gentoo-stage3-latest-3003-1-py3
-      - gentoo-stage3-systemd-3003-1-py3
-      - gentoo-stage3-latest-3002-6-py3
-      - gentoo-stage3-systemd-3002-6-py3
-      - gentoo-stage3-latest-3001-7-py3
-      - gentoo-stage3-systemd-3001-7-py3
-      - gentoo-stage3-latest-3000-9-py3
-      - gentoo-stage3-systemd-3000-9-py3
     provisioner:
       state_top:
         base:
           '*':
             - TEMPLATE._mapdata
             - TEMPLATE
-      pillars:
-        top.sls:
-          base:
-            '*':
-              - TEMPLATE
-              - define_roles
+      pillars: {}
       pillars_from_files:
         TEMPLATE.sls: pillar.example
-        define_roles.sls: test/salt/pillar/define_roles.sls
-    verifier:
-      inspec_tests:
-        - path: test/integration/default
-  - name: gentoo
-    includes:
-      - gentoo-stage3-latest-master-py3
-      - gentoo-stage3-systemd-master-py3
-      - gentoo-stage3-latest-3003-1-py3
-      - gentoo-stage3-systemd-3003-1-py3
-      - gentoo-stage3-latest-3002-6-py3
-      - gentoo-stage3-systemd-3002-6-py3
-      - gentoo-stage3-latest-3001-7-py3
-      - gentoo-stage3-systemd-3001-7-py3
-      - gentoo-stage3-latest-3000-9-py3
-      - gentoo-stage3-systemd-3000-9-py3
-    provisioner:
-      state_top:
-        base:
-          '*':
-            - TEMPLATE._mapdata
-            - TEMPLATE
-      pillars:
-        top.sls:
-          base:
-            '*':
-              - TEMPLATE
-              - gentoo
-              - define_roles
-      pillars_from_files:
-        TEMPLATE.sls: pillar.example
-        gentoo.sls: test/salt/pillar/gentoo.sls
-        define_roles.sls: test/salt/pillar/define_roles.sls
+      pillars_from_directories:
+        - test/salt/pillar
     verifier:
       inspec_tests:
         - path: test/integration/default

test/salt/pillar/top.sls

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+base:
+  '*':
+    - TEMPLATE
+    - define_roles
+  'os_family:Gentoo':
+    - match: grain
+    - gentoo
+...