pixiv: remove fanbox support.

This is broken and it needs to be rewritten as a separate source
strategy anyway.

test/unit/downloads/pixiv_test.rb

@@ -122,17 +122,6 @@ module Downloads
           assert_downloaded(@file_size, @file_url, @ref)
         end
       end
-
-      context "downloading a pixiv fanbox image" do
-        should_eventually "work" do
-          @source = "https://www.pixiv.net/fanbox/creator/12491073/post/82406"
-          @file_url = "https://fanbox.pixiv.net/images/post/82406/D833IKA7FIesJXL8xx39rrG0.jpeg"
-          @file_size = 873_387
-
-          assert_not_rewritten(@file_url, @source)
-          assert_downloaded(@file_size, @file_url, @source)
-        end
-      end
     end
 
     context "An ugoira site for pixiv" do

test/unit/sources/pixiv_test.rb

@@ -73,17 +73,6 @@ module Sources
         end
       end
 
-      context "A https://www.pixiv.net/fanbox/creator/*/post/* source" do
-        should_eventually "work" do
-          @site = Sources::Strategies.find("http://www.pixiv.net/fanbox/creator/554149/post/82555")
-
-          assert_equal("TYONE(お仕事募集中)", @site.artist_name)
-          assert_equal("https://www.pixiv.net/member.php?id=554149", @site.profile_url)
-          assert_equal("https://fanbox.pixiv.net/images/post/82555/Lyyeb6dDLcQZmy09nqLZapuS.jpeg", @site.image_url)
-          assert_nothing_raised { @site.to_h }
-        end
-      end
-
       context "A https://www.pixiv.net/*/artworks/* source" do
         should "work" do
           @site = Sources::Strategies.find("https://www.pixiv.net/en/artworks/64476642")