Commit Message: Add a CPU utilization resource monitor for overload manager
Additional Description: Adds a new resource monitor to be used in CPU bound workloads to shed load. i.e. this can be configured to reject requests once CPU Utilization reaches a certain brownout point.

In my company, we experience user driven retry storms and/or unexpected flash crowds that are mitigated via auto scaling of our compute resources. However, auto scaling takes time and we still want to keep our fleet reasonably healthy during auto scaling and having a way to cheaply reject requests via overload manager has been very helpful. As a platform owner, it is easier to configure limits for CPU bound workloads with this resource monitor than other RPS/Latency/Concurrency based limiters.

Risk Level: Low
Testing: Unit tests
Docs Changes:
Release Notes:
Platform Specific Features: Today this is only implemented for Linux

Request variables

Key	Value
ref	b274d7f
sha	f63d1dc
pr	34713
base-sha	54b2e86
actor	@cancecen
message	Add a CPU utilization resource monitor for overload manager...
started	1726080200.21701
target-branch	main
trusted	false

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