istio update to 1.21.1-bb.1

Package Merge Request

Package Changes

https://repo1.dso.mil/big-bang/product/packages/istio-controlplane/-/blob/1.21.1-bb.1/CHANGELOG.md

Package MR

big-bang/product/packages/istio-controlplane!246 (merged) https://repo1.dso.mil/big-bang/product/packages/istio-controlplane!213

For Issue

This works towards these, but doesn't close them:

• big-bang/product/packages/gitlab#215 (closed)
• big-bang/product/packages/gitlab-runner#69 (closed)

Closes big-bang/product/packages/istio-controlplane#143 (closed)

Upgrade Notices

This removes the upgrade notice for Istio 1.20.4bb.2 as sidecars will not be turned on by default.