Add nodesets.yaml and stop using tmpfs for docker

Change-Id: I6fa07a45f491e7101f85cb90731611409a279719

.zuul.d/base.yaml

@@ -1,4 +1,5 @@
 - job:
+    nodeset: loci-1node-ubuntu_jammy
     name: loci-base
     pre-run: playbooks/setup-gate.yaml
     run: playbooks/loci-builder.yaml

.zuul.d/nodesets.yaml

@@ -0,0 +1,9 @@
+- nodeset:
+    name: loci-1node-ubuntu_jammy
+    nodes:
+      - name: primary
+        label: ubuntu-jammy
+    groups:
+      - name: primary
+        nodes:
+          - primary

playbooks/setup-gate.yaml

@@ -8,24 +8,8 @@
   tasks:
     - include_vars: vars.yaml
 
-    - name: Setup swap
-      block:
-        - command: fallocate -l20g /swap
-        - file:
-            path: /swap
-            mode: 0600
-        - command: mkswap /swap
-        - command: swapon /swap
-      become: True
-
     - name: Install Docker
       block:
-        - mount:
-            path: /var/lib/docker/
-            src: tmpfs
-            fstype: tmpfs
-            opts: size=25g
-            state: mounted
         - include_role:
             name: ensure-docker
         - pip: