logstash: Fix the closed index's error filtering

Test Plan

diff origin/production/logstash0.internal.softwareheritage.org current/logstash0.internal.softwareheritage.org
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  File[/usr/local/bin/es_reopen_closed_indexes.sh] =>
   parameters =>
     content =>
      @@ -23,8 +23,9 @@
      _
       function log_indices() {
      +    local CONDITION="index_closed_exception"
           if [ -z "$1" ]; then
      -        journalctl -x -u logstash | grep "cluster_block" | filter_index_name
      +        journalctl -x -u logstash | grep ${CONDITION} | filter_index_name
           else
      -        tail -n$1 $LOGFILE | grep "cluster_block" | filter_index_name
      +        tail -n$1 $LOGFILE | grep ${CONDITION} | filter_index_name
           fi
       }
*******************************************
*** End octocatalog-diff on logstash0.internal.softwareheritage.org

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Migrated from D7793 (view on Phabricator)