Update tech_stack.yml with Vulnerability Management as owners of Tenable.io

Tech Stack Update

This MR updates the provisioner & ownership of Tenable.io to the Vulnerability Management team.

Please do not merge this MR before the Business Systems Analysts have reviewed and approved.

Please take into account:

• If changing provisioners: You must also open an Update Tech Stack provisioner issue so all templates and Tech Stack information can be updated.
• If completing a system offboarding:
  • Open an issue for Tech Stack offboarding

Security Risk (@gitlab-com/gl-security/security-assurance/security-risk-team )

Not required prior to merging

• Once updates are finalized, reconcile changes with the ZenGRC System of Record

/cc @marc_disabatino @gitlab-com/gl-security/security-assurance/security-risk-team