Move Geo exceptions ee/lib/gitlab/geo.rb to fix autoload issues

Closes #4970

ee/lib/gitlab/geo.rb

@@ -2,6 +2,8 @@ module Gitlab
   module Geo
     OauthApplicationUndefinedError = Class.new(StandardError)
     GeoNodeNotFoundError = Class.new(StandardError)
+    InvalidDecryptionKeyError = Class.new(StandardError)
+    InvalidSignatureTimeError = Class.new(StandardError)
 
     CACHE_KEYS = %i(
       geo_primary_node

ee/lib/gitlab/geo/jwt_request_decoder.rb

 module Gitlab
   module Geo
-    InvalidDecryptionKeyError = Class.new(StandardError)
-    InvalidSignatureTimeError = Class.new(StandardError)
-
     class JwtRequestDecoder
       include LogHelpers