Fix "time" to produce collect Unix time

Currently `time` collector produces a record like this:

    [{"name":"node_time_seconds","value":1.643789173,
      "desc":"System time in seconds since epoch (1970).",
      "ts":1643789173610783251}]

This is very bogus, because it essentially says that the current
system time is `1970-01-01 00:00:01.643789173`. Fix it.

Signed-off-by: Fujimoto Seiji <[email protected]>

Author: fujimotos

lib/fluent/plugin/node_exporter/time_collector.rb

@@ -35,7 +35,7 @@ def run
 
         def time_update
           current_time = Fluent::EventTime.now
-          value = current_time.to_i / 1e9
+          value = current_time.to_i
           @gauge.set(value)
         end