MB-53946: [serverless] Dump the current bucket usage every minute

It looks like the testing of metering has increased and we
currently get bug reports reported from information available
via prometheus (for instance a bug report where kv metering
gets reported as always being 0). It is unknown if this is
a bug where the the information _isn't_ being collected
in memcached; it isn't being reported to prometheus.

This patch dumps the current bucket usage every minute

Change-Id: Ib084295e1f949f16e80f8fc8c89e8c5eb17671d5
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/180709
Reviewed-by: James H <james.harrison@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

daemon/buckets.cc

@@ -256,6 +256,10 @@ void Bucket::tick() {
             }
         }
     });
+
+    if (isServerlessDeployment() && mc_time_get_current_time() % 60 == 0) {
+        LOG_INFO("Bucket usage: {}", to_json().dump());
+    }
 }
 
 void Bucket::deleteThrottledCommands() {