Add Missing Network Policy for SSO

General MR

Summary

• Added missing network policy

Relevant logs/screenshots

Error received when browsing to Prometheus without network policy in place

After application of network policy

**Note: The 2739-istiod-sso-fix branch of Big Bang will need to be used as the missing network policy was only part of the fix. The updates made in this branch will be ported to the BB MR that gets opened to bump the tag.

Linked Issue

issue

Upgrade Notices

N/A