Remove Cloudflare __cfduid cookie configs (#20071)

* Remove Cloudflare __cfduid cookie configs

This cookie is no longer set for any requests proxied via Cloudflare and
thus the configs that were added for it can be removed.

Further context from Cloudflare's blog:
https://blog.cloudflare.com/deprecating-cfduid-cookie/

* Delete obsolete placehold.it rule

The hosts related to placehold.it are no longer serving a valid
certificate so the https rule for them no longer makes sense.

Author: migueldemoura

src/chrome/content/rules/Freegeoip.net.xml

@@ -6,7 +6,7 @@
 	<target host="www.freegeoip.net" />
 
 
-	<securecookie host="^\.freegeoip\.net$" name="^(?:__cfuid|cf_clearance)$" />
+	<securecookie host="^\.freegeoip\.net$" name="^cf_clearance$" />
 
 
 	<rule from="^http:"

src/chrome/content/rules/OkCimg.com.xml

@@ -30,7 +30,7 @@ Fetch error: http://ads.okcimg.com/ => https://ads.okcimg.com/: (28, 'Operation
 
 	<!--	Not secured by server:
 					-->
-	<!--securecookie host="^\.okcimg\.com$" name="^(__cfuid|cf_clearance|guest)$" /-->
+	<!--securecookie host="^\.okcimg\.com$" name="^(cf_clearance|guest)$" /-->
 
 	<securecookie host="^\.okcimg\.com$" name=".+" />
 

src/chrome/content/rules/Pando.xml

@@ -12,7 +12,7 @@
 
 	<!--	CloudFlare cookies:
 					-->
-	<!--securecookie host="^\.pando\.com$" name="^(?:__cfuid|cf_clearance)$" /-->
+	<!--securecookie host="^\.pando\.com$" name="^cf_clearance$" /-->
 
 	<securecookie host=".+" name=".+" />
 

src/chrome/content/rules/Placehold.it.xml

@@ -12,7 +12,7 @@
 
 	<!--	CloudFlare cookies:
 					-->
-	<!--securecookie host="^\.weusecoins\.com$" name="^(__cfuid|cf_clearance)$" /-->
+	<!--securecookie host="^\.weusecoins\.com$" name="^cf_clearance$" /-->
 
 	<securecookie host=".+" name=".+" />