Drop pip-and-virtualenv from images

As discussed at [1] this removes the pip-and-virtualenv element from
images that still have it.

For now we leave the old templating bits so we can easily revert an
image if there are unavoidable issues.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-May/015157.html

Change-Id: I76befd9e2a054798e8e36500b723870f7c7ae328

nodepool/nodepool.yaml

@@ -154,7 +154,7 @@ diskimages:
   ############ CentOS and Fedora #############
 
   - name: centos-7
-    parent: base-with-pip
+    parent: base
     pause: false
     elements:
       - centos-minimal
@@ -164,7 +164,7 @@ diskimages:
       DIB_EPEL_DISABLED: '1'
 
   - name: centos-8
-    parent: base-with-pip
+    parent: base
     pause: false
     python-path: /usr/bin/python3
     release: '8'
@@ -176,7 +176,7 @@ diskimages:
       DIB_EPEL_DISABLED: '1'
 
   - name: fedora-30
-    parent: base-with-pip
+    parent: base
     pause: false
     python-path: /usr/bin/python3
     elements:
@@ -196,7 +196,7 @@ diskimages:
   ############ Debian #############
 
   - name: debian-stretch
-    parent: base-debuntu-with-pip
+    parent: base-debuntu
     pause: false
     elements:
       - debian-minimal
@@ -209,7 +209,7 @@ diskimages:
       DIB_DEBIAN_SECURITY_SUBPATH: ''
 
   - name: debian-buster
-    parent: base-debuntu-with-pip
+    parent: base-debuntu
     pause: false
     elements:
       - debian-minimal
@@ -244,7 +244,7 @@ diskimages:
   ############ Gentoo #############
 
   - name: gentoo-17-0-systemd
-    parent: base-with-pip
+    parent: base
     pause: true
     elements:
       - gentoo
@@ -282,7 +282,7 @@ diskimages:
   ############ Ubuntu #############
 
   - name: ubuntu-bionic
-    parent: base-debuntu-with-pip
+    parent: base-debuntu
     pause: false
     elements:
       - ubuntu-minimal
@@ -304,7 +304,7 @@ diskimages:
       DIB_DEBIAN_COMPONENTS: 'main,universe'
 
   - name: ubuntu-xenial
-    parent: base-debuntu-with-pip
+    parent: base-debuntu
     pause: false
     elements:
       - ubuntu-minimal