logstash: explicitely match not number facility ids

because \d is not working for field values in string like "4"

Related to T3705

site-modules/profile/templates/logstash/filter.conf.erb

@@ -30,7 +30,7 @@ filter {
       }
     }
   } else {
-    if [syslog][facility] !~ /^\d+$/ {
+    if [syslog][facility] =~ /[A-Za-z]+/ {
       mutate {
         rename => { "[syslog][facility]" => "[syslog][facility_name]" }
       }

[Phabricator Migration user]

Some references in the commit message have been migrated:

• T3705 is now swh/meta#3705 (closed)