fix(istiod): removed CPU limit overrides

General MR

Summary

This MR just removes the overrides for CPU limits that were added in the previous commit. Unfortunately, setting these CPU limits to null causes istiod to set the limits to 0 in injected sidecars, less than the CPU request of 100m and breaks sidecar injection.

Relevant logs/screenshots

This MR has pipelines that failed due to this issue and also a pipeline that passed once the limits were set: big-bang/bigbang!6186 (merged)

Linked Issue

#30 (closed)

Upgrade Notices

N/A