Close and reopen security agent logs

[rvansa]

An application run with -Dnewrelic.config.security.agent.enabled=true -Dnewrelic.config.security.enabled=true cannot be checkpointed as these two logs remain open.

Some concerns I would like the reviewer to clear up:

• I have not checked the exact semantics of shadowIntoJar, but since the main newrelic-java-agent shadows org.crac:crac as well, are we duplicating this? Could we have only shared instance?
• Exceptions thrown when closing the logs are silently swallowed; should I just print them to stderr?
• The synchronization through the executor should be safe with regards to regular logging; there's LogFileHelper.performDailyRollover(), though, and this does not use any synchronization when updating non-volatile field. The C/R code is affected the same way as regular logging code.

Thank you!

[CLAassistant]

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