fluentd-plugin-grafana-loki: change log.info to log.debug (#751)

Reduces background chatter which in turn can trigger more log writes

Signed-off-by: Brian Candler <b.candler@pobox.com>

fluentd/fluent-plugin-grafana-loki/lib/fluent/plugin/out_loki.rb

@@ -97,7 +97,7 @@ def write(chunk)
         opts = {
           use_ssl: uri.scheme == 'https'
         }
-        log.info "sending #{req.body.length} bytes"
+        log.debug "sending #{req.body.length} bytes to loki"
         res = Net::HTTP.start(uri.hostname, uri.port, **opts) { |http| http.request(req) }
         unless res && res.is_a?(Net::HTTPSuccess)
           res_summary = if res