RUBY-3814 Remove dead code

lib/mongo/auth/aws/conversation.rb

@@ -74,10 +74,6 @@ def client_first_payload
           client_first_data.to_bson.to_s
         end
 
-        def wrap_data(data)
-          BSON::Binary.new(data.to_bson.to_s)
-        end
-
         def client_nonce
           @client_nonce ||= SecureRandom.random_bytes(32)
         end

lib/mongo/auth/scram_conversation_base.rb

@@ -281,13 +281,6 @@ def hmac(data, key)
       # @since 2.0.0
       attr_reader :iterations
 
-      # Get the data from the returned payload.
-      #
-      # @api private
-      #
-      # @since 2.0.0
-      attr_reader :payload_data
-
       # Get the server nonce from the payload.
       #
       # @api private

lib/mongo/auth/stringprep.rb

@@ -97,12 +97,7 @@ def mapping(c, mappings)
       end
 
       def normalize!(out)
-        if String.method_defined?(:unicode_normalize!)
-          out.unicode_normalize!(:nfkc)
-        else
-          require 'mongo/auth/stringprep/unicode_normalize/normalize'
-          out.replace(UnicodeNormalize.normalize(out, :nfkc))
-        end
+        out.unicode_normalize!(:nfkc)
       end
 
       def table_contains?(table, c)