Add vexxhost provider and build raw images

To test building and uploading a raw image, add a vexxhost provider
and also tell the image build job to build a raw image.

Vexxhost does not have a "normal" flavor, so no flavors or labels
are added to it.  We will only upload images to it.

Change-Id: I38005072637dc5b60ef7f58caa980bb7595c3907

zuul.d/jobs.yaml

@@ -33,6 +33,7 @@
       # TODO(corvus): This will eventually be supplied by Zuul
       build_diskimage_formats:
         - qcow2
+        - raw
       build_diskimage_elements: &base_elements
         - vm
         - simple-init

zuul.d/providers.yaml

@@ -1,3 +1,4 @@
+# Rackspace Flex
 - section:
     name: raxflex-base
     abstract: true
@@ -23,3 +24,22 @@
     labels:
       - name: niz-debian-bullseye-normal
         key-name: infra-root-keys-2024-04-08
+
+# Vexxhost
+- section:
+    name: vexxhost-base
+    abstract: true
+    connection: vexxhost
+    boot-timeout: 120
+    launch-timeout: 600
+    images:
+      - name: debian-bullseye
+
+- section:
+    name: vexxhost-ca-ymq-1
+    parent: vexxhost-base
+    region: ca-ymq-1
+
+- provider:
+    name: vexxhost-ca-ymq-1-main
+    section: vexxhost-ca-ymq-1