Update to using pike cloud-archive

Now that Pike has been released, switch to using the pike version of
UCA instead of ocata, too.

One reason to do so it that it adds python3-ceph packages, allow to have
progress with the python3 compatibility of the Ceph integration.

Change-Id: I7d95e53892b697c72af75ad0ce7ce2dec6d31fde
diff --git a/tools/fixup_stuff.sh b/tools/fixup_stuff.sh
index f1552ab..efe0125 100755
--- a/tools/fixup_stuff.sh
+++ b/tools/fixup_stuff.sh
@@ -84,10 +84,10 @@
         # we can find local mirrors then use that mirror.
         source /etc/ci/mirror_info.sh
 
-        sudo apt-add-repository -y "deb $NODEPOOL_UCA_MIRROR xenial-updates/ocata main"
+        sudo apt-add-repository -y "deb $NODEPOOL_UCA_MIRROR xenial-updates/pike main"
     else
         # Otherwise use upstream UCA
-        sudo add-apt-repository -y cloud-archive:ocata
+        sudo add-apt-repository -y cloud-archive:pike
     fi
 
     # Disable use of libvirt wheel since a cached wheel build might be