Drop nova-multiattach job

The dependent tempest change enables the volume multiattach
tests in the tempest-full and tempest-slow jobs, on which
nova already gates, which allows us to drop the special
nova-multiattach job which is mostly redundant test coverage
of the other tempest.api.compute.* tests, and allows us to
run one fewer job on nova/cinder/tempest changes in Stein.

The docs are updated to reflect the source of the testing
now.

Also depends on cinder dropping its usage of the nova-multiattach
job before we can drop the job definition from nova.

Depends-On: https://review.openstack.org/606978
Depends-On: https://review.openstack.org/606985
Change-Id: I744afa1df9a6ed8e0eba4310b20c33755ce1ba88

playbooks/legacy/nova-multiattach/post.yaml

@@ -1,15 +0,0 @@
-- hosts: primary
-  tasks:
-
-    - name: Copy files from {{ ansible_user_dir }}/workspace/ on node
-      synchronize:
-        src: '{{ ansible_user_dir }}/workspace/'
-        dest: '{{ zuul.executor.log_root }}'
-        mode: pull
-        copy_links: true
-        verify_host: true
-        rsync_opts:
-          - --include=/logs/**
-          - --include=*/
-          - --exclude=*
-          - --prune-empty-dirs

playbooks/legacy/nova-multiattach/run.yaml

@@ -1,53 +0,0 @@
-- hosts: all
-  name: nova-multiattach
-  tasks:
-
-    - name: Ensure workspace directory
-      file:
-        path: '{{ ansible_user_dir }}/workspace'
-        state: directory
-
-    - shell:
-        cmd: |
-          set -e
-          set -x
-          cat > clonemap.yaml << EOF
-          clonemap:
-            - name: openstack-infra/devstack-gate
-              dest: devstack-gate
-          EOF
-          /usr/zuul-env/bin/zuul-cloner -m clonemap.yaml --cache-dir /opt/git \
-              git://git.openstack.org \
-              openstack-infra/devstack-gate
-        executable: /bin/bash
-        chdir: '{{ ansible_user_dir }}/workspace'
-      environment: '{{ zuul | zuul_legacy_vars }}'
-
-    - shell:
-        cmd: |
-          set -e
-          set -x
-          cat << 'EOF' >>"/tmp/dg-local.conf"
-          [[local|localrc]]
-          ENABLE_VOLUME_MULTIATTACH=True
-
-          EOF
-        executable: /bin/bash
-        chdir: '{{ ansible_user_dir }}/workspace'
-      environment: '{{ zuul | zuul_legacy_vars }}'
-
-    - shell:
-        cmd: |
-          set -e
-          set -x
-          export PYTHONUNBUFFERED=true
-          # Yes we want to run Tempest.
-          export DEVSTACK_GATE_TEMPEST=1
-          # Only run compute API tests; note that this will need to
-          # be updated if multiattach scenario tests are ever added.
-          export DEVSTACK_GATE_TEMPEST_REGEX="api.compute"
-          cp devstack-gate/devstack-vm-gate-wrap.sh ./safe-devstack-vm-gate-wrap.sh
-          ./safe-devstack-vm-gate-wrap.sh
-        executable: /bin/bash
-        chdir: '{{ ansible_user_dir }}/workspace'
-      environment: '{{ zuul | zuul_legacy_vars }}'