[core_manager] Don't delete cores during outputSummary.
[core_manager] Don't delete cores during outputSummary.

mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite,victorisildur/Graphite,victorisildur/Graphite,mit-carbon/Graphite,victorisildur/Graphite,mit-carbon/Graphite-Cycle-Level,8l/Graphite,mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite,fhijaz/Graphite,8l/Graphite,8l/Graphite,mit-carbon/Graphite-Cycle-Level,nkawahara/Graphite,mit-carbon/Graphite,nkawahara/Graphite,fhijaz/Graphite,nkawahara/Graphite,victorisildur/Graphite,fhijaz/Graphite,nkawahara/Graphite,8l/Graphite,fhijaz/Graphite