3scale Developer Portal is not found when the file storage is S3

Issue

• When clicking the "Visit Developer Portal", the "Not Found" page is displayed.
• A system-sidekiq pod logged Aws::S3::Errors::AccessDenied repeatedly.

2030-01-01T07:44:39.598570497Z Exception -- {:exception=>{:class=>Aws::S3::Errors::AccessDenied, :message=>"Access Denied", :backtrace=>["/opt/system/vendor/bundle/ruby/2.4.0/gems/aws-sdk-core-2.6.34/lib/seahorse/client/plugins/raise_response_errors.rb:15:in `call'", "/opt/system/vendor/bundle/ruby/2.4.0/gems/aws-sdk-core-2.6.34/lib/aws-sdk-core/plugins/s3_sse_cpk.rb:19:in `call'", "/opt/system/vendor/bundle/ruby/2.4.0/gems/aws-sdk-core-2.6.34/lib/aws-sdk-core/plugins/s3_dualstack.rb:24:in `call'", "/opt/system/vendor/bundle/ruby/2.4.0/gems/aws-sdk-core-2.6.34/lib/aws-sdk-core/plugins/s3_accelerate.rb:34:in `call'"]}, :parameters=>{:context=>"Job raised exception", :job=>{"class"=>"SignupWorker::ImportSimpleLayoutWorker", "args"=>[31], "retry"=>true, "queue"=>"critical", "jid"=>"3f8f514dd69f2bf32bd83e4f", "created_at"=>1111111111.7777777, "bid"=>"xxxxxxxxxxxxxx", "enqueued_at"=>1111111111.7777777, "error_message"=>"Access Denied", "error_class"=>"Aws::S3::Errors::AccessDenied", "failed_at"=>1590382720.7913878, "retry_count"=>9, "retried_at"=>1590392679.597766}, :jobstr=>"{\"class\":\"SignupWorker::ImportSimpleLayoutWorker\",\"args\":[31],\"retry\":true,\"queue\":\"critical\",\"jid\":\"xxxxxxxxxxx\",\"created_at\":1590382720.7776194,\"bid\":\"xxxxxxxxxxxxxx\",\"enqueued_at\":1590392679.0498593,\"error_message\":\"Access Denied\",\"error_class\":\"Aws::S3::Errors::AccessDenied\",\"failed_at\":1590382720.7913878,\"retry_count\":8,\"retried_at\":1590388421.2085843}"}}