rm reference to old constant (from Rails v2.2) (getsentry#1184)

CGI::Session::CookieStore::TamperedWithCookie was originally referenced
by Raven in a refactor of its backtrace cleaner in 2012.

  https://github.com/getsentry/sentry-ruby/pull/58/files#diff-2337b0e4ecfcd526e8dbf0aa6f3a5570a2228c2cc71afdf6ba0edd4d361a40c2R45

CGI::Session::CookieStore was removed from Rails in 2008 when ActionPack
switched to using Rack-based sessions.

  rails/rails@ed70830#diff-018dc029403b3cf53f21aef6fc77debda6e09c0739f6d7ff6a1331e40e5135eaL48

sentry-ruby/lib/sentry/configuration.rb

@@ -134,7 +134,6 @@ class Configuration
     # Most of these errors generate 4XX responses. In general, Sentry clients
     # only automatically report 5xx responses.
     IGNORE_DEFAULT = [
-      'CGI::Session::CookieStore::TamperedWithCookie',
       'Mongoid::Errors::DocumentNotFound',
       'Rack::QueryParser::InvalidParameterError',
       'Rack::QueryParser::ParameterTypeError',