[firewall config] please update the udd-mirror.debian.net ip address

[Paride Legovini]

Hi,

Apparently the IP address of udd-mirror.debian.net changed and it's not 
reachable anymore from the Jenkins nodes. This is causing failures in 
some metrics collecting jobs.

Past RT on the same issue: https://portal.admin.canonical.com/C120719/

This should be fix it:


--- a/external/debian.yaml
+++ b/external/debian.yaml
@@ -36,4 +36,4 @@ debian:
      svn:
      - 5.153.231.21
      udd-mirror:
-    - 18.25.134.246
+    - 147.75.35.146


Thanks!

Paride