Fix ActivityPub handling of replies with WEB_DOMAIN (#4895) (#4904)

* Fix ActivityPub handling of replies when LOCAL_DOMAIN ≠ WEB_DOMAIN (#4895)

For all intents and purposes, `local_url?` is used to check if an URL refers
to the Web UI or the various API endpoints of the local instances. Those things
reside on `WEB_DOMAIN` and not `LOCAL_DOMAIN`.

* Change local_url? spec, as all URLs handled by Mastodon are based on WEB_DOMAIN

app/lib/tag_manager.rb

@@ -87,7 +87,7 @@ class TagManager
   def local_url?(url)
     uri    = Addressable::URI.parse(url).normalize
     domain = uri.host + (uri.port ? ":#{uri.port}" : '')
-    TagManager.instance.local_domain?(domain)
+    TagManager.instance.web_domain?(domain)
   end
 
   def uri_for(target)

spec/lib/tag_manager_spec.rb

@@ -63,23 +63,23 @@ RSpec.describe TagManager do
 
   describe '#local_url?' do
     around do |example|
-      original_local_domain = Rails.configuration.x.local_domain
+      original_web_domain = Rails.configuration.x.web_domain
       example.run
-      Rails.configuration.x.local_domain = original_local_domain
+      Rails.configuration.x.web_domain = original_web_domain
     end
 
     it 'returns true if the normalized string with port is local URL' do
-      Rails.configuration.x.local_domain = 'domain:42'
+      Rails.configuration.x.web_domain = 'domain:42'
       expect(TagManager.instance.local_url?('https://DoMaIn:42/')).to eq true
     end
 
     it 'returns true if the normalized string without port is local URL' do
-      Rails.configuration.x.local_domain = 'domain'
+      Rails.configuration.x.web_domain = 'domain'
       expect(TagManager.instance.local_url?('https://DoMaIn/')).to eq true
     end
 
     it 'returns false for string with irrelevant characters' do
-      Rails.configuration.x.local_domain = 'domain'
+      Rails.configuration.x.web_domain = 'domain'
       expect(TagManager.instance.local_url?('https://domainn/')).to eq false
     end
   end