Remove piwik.org from default whitelist

See:
https://www.reddit.com/r/qutebrowser/comments/cxi2m3/why_is_pywikorg_whitelisted/

doc/help/settings.asciidoc

@@ -1867,9 +1867,7 @@ Local domains are always exempt from hostblocking.
 
 Type: <<types,List of UrlPattern>>
 
-Default: 
-
-- +pass:[piwik.org]+
+Default: empty
 
 [[content.hyperlink_auditing]]
 === content.hyperlink_auditing

qutebrowser/config/configdata.yml

@@ -522,8 +522,7 @@ content.host_blocking.lists:
     The file `~/.config/qutebrowser/blocked-hosts` is always read if it exists.
 
 content.host_blocking.whitelist:
-  default:
-  - piwik.org
+  default: []
   type:
     name: List
     valtype: UrlPattern