docs(3.0): added notice about OCI artifact naming issues with istioGateway

General MR

Summary

This MR adds a notice to the BB 3.0 migration guide outlining the issues with OCI artifacts in the 3.0 migration and steps customers should take to mitigate it.

Relevant Links

The appropriate section of the rendered migration guide.

Linked Issue

Closes #2790 (closed)

Upgrade Notices

N/A