Remove opensuse-15 image builds from nodepool

This should be landed after the parent chagne has landed and nodepool
has successfully deleted all opensuse-15 image uploads from our cloud
providers. At this point it should be safe to remove the image builds
entirely.

Change-Id: Icc870ce04b0f0b26df673f85dd6380234979906f

nodepool/nb04.opendev.org.yaml

@@ -176,11 +176,6 @@ diskimages:
   - name: gentoo-17-0-systemd
     elements: []
 
-  ############ openSUSE #############
-
-  - name: opensuse-15
-    elements: []
-
   ############ Ubuntu #############
 
   - name: ubuntu-bionic

nodepool/nl01.opendev.org.yaml

@@ -195,7 +195,6 @@ diskimages:
   - name: debian-bullseye
   - name: debian-buster
   - name: gentoo-17-0-systemd
-  - name: opensuse-15
   - name: rockylinux-8
   - name: rockylinux-9
   - name: ubuntu-bionic

nodepool/nl02.opendev.org.yaml

@@ -171,7 +171,6 @@ diskimages:
   - name: debian-bullseye
   - name: debian-buster
   - name: gentoo-17-0-systemd
-  - name: opensuse-15
   - name: rockylinux-8
   - name: rockylinux-9
   - name: ubuntu-bionic

nodepool/nl03.opendev.org.yaml

@@ -541,7 +541,6 @@ diskimages:
   - name: debian-buster
   - name: debian-buster-arm64
   - name: gentoo-17-0-systemd
-  - name: opensuse-15
   - name: rockylinux-8
   - name: rockylinux-9
   - name: rockylinux-9-arm64

nodepool/nl04.opendev.org.yaml

@@ -224,7 +224,6 @@ diskimages:
   - name: debian-bullseye
   - name: debian-buster
   - name: gentoo-17-0-systemd
-  - name: opensuse-15
   - name: rockylinux-8
   - name: rockylinux-9
   - name: ubuntu-bionic

nodepool/nodepool.yaml

@@ -338,23 +338,6 @@ diskimages:
       GENTOO_PYTHON_ACTIVE_VERSION: python3.9
       GENTOO_PROFILE: 'default/linux/amd64/17.1/systemd'
 
-
-  ############ openSUSE #############
-
-  - name: opensuse-15
-    parent: base
-    # NOTE(ianw): Paused 2020-12-18 due to persistent build failures
-    # pending investigation. Unpausing as images were deleted and we need
-    # new builds to debug.
-    pause: false
-    elements:
-      - opensuse-minimal
-      - cache-devstack
-    release: '15.2'
-    python-path: /usr/bin/python3
-    env-vars:
-      DIB_DISTRIBUTION_MIRROR: 'https://mirror.dfw.rax.opendev.org/opensuse'
-
   ############ Ubuntu #############
 
   - name: ubuntu-bionic