Log deprecated metrics (#340)

Co-authored-by: Georgy Moiseev <[email protected]>

Author: yngvar-antonsson

metrics/init.lua

@@ -119,6 +119,9 @@ return {
     invoke_callbacks = invoke_callbacks,
     set_global_labels = set_global_labels,
     enable_default_metrics = function(include, exclude)
+        log.warn('metrics tnt_net_sent_rps, tnt_net_received_rps, tnt_net_connections_rps, '..
+            'tnt_net_requests_rps, tnt_stats_op_rps ' ..
+            'are deprecated and will be removed in next releases.')
         require('metrics.tarantool').enable(include, exclude)
     end,
     enable_cartridge_metrics = function()