Improve rate limiting (mastodon#10860)

* Rate limit based on remote address IP, not on potential reverse proxy

* Limit rate of unauthenticated API requests further

* Rate-limit paging requests to one every 3 seconds

config/initializers/rack_attack.rb

@@ -58,7 +58,7 @@ def paging_request?
   end
 
   throttle('throttle_unauthenticated_api', limit: 300, period: 5.minutes) do |req|
-    req.remote_ip if req.api_request? && req.unauthenticated?
+    req.remote_ip if req.api_request? && !req.authenticated?
   end
 
   throttle('throttle_api_media', limit: 300, period: 5.minutes) do |req|
@@ -70,7 +70,7 @@ def paging_request?
   end
 
   throttle('throttle_unauthenticated_media_proxy', limit: 30, period: 30.minutes) do |req|
-    req.remote_ip if req.unauthenticated? && req.path.start_with?('/media_proxy')
+    req.remote_ip if !req.authenticated? && req.path.start_with?('/media_proxy')
   end
 
   throttle('throttle_api_sign_up', limit: 5, period: 30.minutes) do |req|
@@ -83,7 +83,7 @@ def paging_request?
   end
 
   throttle('throttle_unauthenticated_paging', limit: 300, period: 15.minutes) do |req|
-    req.remote_ip if req.paging_request? && req.unauthenticated?
+    req.remote_ip if req.paging_request? && !req.authenticated?
   end
 
   API_DELETE_REBLOG_REGEX = /\A\/api\/v1\/statuses\/[\d]+\/unreblog/.freeze