Try switching Rackspace DFW to an API key

Switch the Rackspace region with the smallest quota to uploading
images and booting server instances with our account's API key
instead of its password, in preparation for their MFA transition. If
this works as expected, we'll make a similar switch for the
remaining two regions.

Change-Id: I97887063c735c96d200ce2cbd8950bbec0ef7240
Depends-On: https://review.opendev.org/911164

nodepool/nl01.opendev.org.yaml

@@ -46,7 +46,7 @@ labels:
 providers:
   - name: rax-dfw
     region-name: 'DFW'
-    cloud: rax
+    cloud: rackspace
     boot-timeout: 120
     launch-timeout: 600
     rate: 0.001

nodepool/nodepool.yaml

@@ -56,7 +56,7 @@ providers:
 
   - name: rax-dfw
     region-name: 'DFW'
-    cloud: rax
+    cloud: rackspace
     rate: 0.001
     # 6 hours
     image-upload-timeout: 21600