make Gentoo use the systemd profile

Also, use the default DIB variables.

Depends-On: https://review.openstack.org/548604
Change-Id: I155413f02c18f78e6a3746c230e9c72ccdf08105

nodepool/nodepool.yaml

@@ -45,6 +45,8 @@ providers:
         config-drive: true
       - name: fedora-27
         config-drive: true
+      - name: gentoo-17-0-systemd
+        config-drive: true
       - name: opensuse-423
         config-drive: true
       - name: opensuse-tumbleweed
@@ -176,7 +178,7 @@ diskimages:
       DIB_IMAGE_CACHE: /opt/dib_cache
       QEMU_IMG_OPTIONS: compat=0.10
       DIB_GRUB_TIMEOUT: '0'
-  - name: gentoo
+  - name: gentoo-17-0-systemd
     pause: false
     elements:
       - gentoo
@@ -192,11 +194,9 @@ diskimages:
       DIB_IMAGE_CACHE: /opt/dib_cache
       QEMU_IMG_OPTIONS: compat=0.10
       DIB_GRUB_TIMEOUT: '0'
-      GENTOO_PORTAGE_CLEANUP: 'True'
-      DIB_INSTALLTYPE_pip_and_virtualenv: 'package'
-      DIB_INSTALLTYPE_simple_init: 'repo'
       GENTOO_PYTHON_TARGETS: 'python2_7 python3_5'
       GENTOO_PYTHON_ACTIVE_VERSION: python3.5
+      GENTOO_PROFILE: 'default/linux/amd64/17.0/systemd'
   - name: opensuse-423
     pause: false
     elements: