source-zendesk-support: checkpoint TicketMetricEvents state after e…

…very 1000 documents

Previously, `TicketMetricEvents` was only emitting documents and
checkpointing state after reading all available documents from Zendesk
Support. `TicketMetricEvents` can take multiple hours to backfill, and
any task restarts during the backfill caused `TicketMetricEvents` to
start over completely instead of picking back up where it left off
before the restart.

Setting `state_checkpoint_interval` tells `TickeMetricEvents` to
checkpoint state & emit documents after every 1000 documents and allows
the stream to pick up where it left off if it's interrupted during a
backfill.

source-zendesk-support/source_zendesk_support/streams.py

@@ -932,6 +932,7 @@ class TicketMetricEvents(SourceZendeskSupportCursorPaginationStream):
     TicketMetricEvents stream: https://developer.zendesk.com/api-reference/ticketing/tickets/ticket_metric_events/
     """
 
+    state_checkpoint_interval = 1000
     cursor_field = "time"
     page_size = 1000