Add JMXFetch to SSI Guardrails denylist

[PerfectSlayer]

What Does This Do

This PR excludes DataDog JMXFetch from the processes being automatically instrumented.

Motivation

There is no use instrumenting JMXFetch and it will add noise while troubleshooting (using flare).

Additional Notes

Contributor Checklist

• Format the title according the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any usefull labels
• Squash your commits prior merging or merge using GitHub's Squash and merge
• Don't use close, fix or any linking keywords when referencing an issue.
  Use solves instead, and assign the PR milestone to the issue
• Update the public documentation in case of new configuration flag or behavior

Jira ticket: APMLP-325

[andrewlock]

LGTM, thanks!