fix: Rack::Attack configuration

[Quentinchampenois]

Describe the bug
A clear and concise description of what the bug is.

We must update the Rack Attack configuration because Rack::Attack is still active in production and causes 429 HTTP status code in case of heavy navigation

[Quentinchampenois]

Backport the PR: https://github.com/OpenSourcePolitics/decidim-app/pull/449/files