Refactor neuvector logic to use existing password if it exists

General MR

Summary

Refactor NeuVector password generation logic to check for existing secret before creating a new one

Relevant logs/screenshots

TBD - Logs showing upgrades that don't always create a new secret

Linked Issue

#2835 (closed)

Upgrade Notices

"N/A"

This should just prevent Neuvector from always upgrading