Revert sentry ignore config to default

Sentry by default ignores:

Sentry::Configuration::IGNORE_DEFAULT
=> ["Mongoid::Errors::DocumentNotFound",
 "Rack::QueryParser::InvalidParameterError",
 "Rack::QueryParser::ParameterTypeError",
 "Sinatra::NotFound"]

and we add config.excluded_exceptions << "ActionController::RoutingError" # We still want to capture 404 in case we link to wrong IDs but Routing Errors are mostly noise caused by bots (sitemap.txt) or script kiddies (wp-login.ph)

follow up for #951 (closed)