Fixup missing checkpoint write time

Was removed in error related to an active bug in postgres_exporter

prometheus-community/postgres_exporter#633

Author: tomswartz07

roles/postgres_exporter/templates/custom-monitor.yml.j2

@@ -208,14 +208,17 @@ ccp_settings_gauge:
 
 
 ccp_stat_bgwriter:
-    query: "SELECT checkpoints_timed, checkpoints_req, checkpoint_sync_time, buffers_checkpoint, buffers_clean, maxwritten_clean, buffers_backend, buffers_backend_fsync, buffers_alloc, stats_reset FROM pg_catalog.pg_stat_bgwriter"
+    query: "SELECT checkpoints_timed, checkpoints_req, checkpoint_write_time, checkpoint_sync_time, buffers_checkpoint, buffers_clean, maxwritten_clean, buffers_backend, buffers_backend_fsync, buffers_alloc, stats_reset FROM pg_catalog.pg_stat_bgwriter"
     metrics:
       - checkpoints_timed:
             usage: "GAUGE"
             description: "Number of scheduled checkpoints that have been performed"
       - checkpoints_req:
             usage: "GAUGE"
             description: "Number of requested checkpoints that have been performed"
+      - checkpoint_write_time:
+            usage: "GAUGE"
+            description: "Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds"
       - checkpoint_sync_time:
             usage: "GAUGE"
             description: "Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds"