Adjust Vault Monitoring to utilize AdditionalScrapeConfig rather than ServiceMonitor

Following on to https://repo1.dso.mil/platform-one/big-bang/apps/sandbox/vault/-/issues/30 which doesn't allow for mounting the authentication information/secret that Vault requires and is injected via the agent, we will instead have to use a scrapeConfig value instead of a ServiceMonitor, see the final step in this Jira document: https://jira.il2.dso.mil/browse/P1CNAP-1794

The above Vault issue will be closed in favor of this one since the setup can go over HTTPS across the istio VirtualService with the configured auth and mTLS connection won't need to be specified.