Bump linkerd2-proxy-init to v2.2.1

Bump linkerd2-proxy-init to v2.2.1: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). The linkerd/linkerd2-proxy-init (https://github.com/linkerd/linkerd2-proxy-init) repo has cut a new release. We should pick up the new versions of all three artifacts it ships:

The task

The [linkerd/linkerd2-proxy-init](https://github.com/linkerd/linkerd2-proxy-init) repo has cut a new release. We should pick up the new versions of all three artifacts it ships:

Part of FineEnvs/MiMo-V2.6-RL-harbor-code.