DEV: Fix failing spec after Rails upgrade to 7.0.5.1 (#22317)

Follow up to 4d3999de10

lib/middleware/discourse_public_exceptions.rb

@@ -49,12 +49,16 @@ module Middleware
           # Or badly formatted multipart requests
           begin
             request.POST
-          rescue EOFError
-            return [
-              400,
-              { "Cache-Control" => "private, max-age=0, must-revalidate" },
-              ["Invalid request"]
-            ]
+          rescue ActionController::BadRequest => error
+            if error.cause.is_a?(EOFError)
+              return [
+                400,
+                { "Cache-Control" => "private, max-age=0, must-revalidate" },
+                ["Invalid request"]
+              ]
+            else
+              raise
+            end
           end
 
           if ApplicationController.rescue_with_handler(exception, object: fake_controller)