feat: allow configuring a temp dir for Ambienty

ansible/roles/radicle-ci-node/defaults/main.yaml

@@ -4,6 +4,10 @@ radicle_ci_ambient_cpus: 1
 # Amount of memory an Ambient virtual machine should have.
 radicle_ci_ambient_memory: 1G
 
+# Temporary directory for Ambient. This will get copies of virtual
+# machine images, so it may grow big.
+radicle_ci_ambient_tmp: /tmp
+
 # Description of CI node on top of CI broker report page. This can contain
 # HTML tags.
 radicle_ci_description: |

ansible/roles/radicle-ci-node/templates/ambient-config.yaml

@@ -7,4 +7,4 @@ qemu:
   cpus: {{ radicle_ci_ambient_cpus }}
   memory: {{ radicle_ci_ambient_memory }}
 lint: false
-
+tmpdir: "{{ radicle_ci_tmp }}"

ansible/roles/radicle-ci-node/templates/radicle-ci-broker.service

@@ -6,6 +6,7 @@ Description=Radicle CI broker
 [Service]
 Type=simple
 Environment=RAD_HOME=/home/ci/.radicle
+Environment=TMPDIR={{ radicle_ci_tmp }}
 ExecStart=/bin/cib --log-level info --config /home/ci/ci.yaml process-events
 KillMode=control-group
 Restart=always