Refactor the kube-scheduler configuration API, command setup, and server
setup according to the guidelines established in #32215 and using the
kube-proxy refactor (#34727) as a model of a well factored component
adhering to said guidelines.
* Config API: clarify meaning and use of algorithm source by replacing
modality derived from bools and string emptiness checks with an explicit
AlgorithmSource type hierarchy.
* Config API: consolidate client connection config with common structs.
* Config API: split and simplify healthz/metrics server configuration.
* Config API: clarify leader election configuration.
* Config API: improve defaulting.
* CLI: deprecate all flags except `--config`.
* CLI: port all flags to new config API.
* CLI: refactor to match kube-proxy Cobra command style.
* Server: refactor away configurator.go to clarify application wiring.
* Server: refactor to more clearly separate wiring/setup from running.
Fixes#52428.
Automatic merge from submit-queue (batch tested with PRs 53903, 53914, 54374). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Add PodDisruptionBudget to scheduler cache.
**What this PR does / why we need it**:
This is the first step to add support for PodDisruptionBudget during preemption. This PR adds PDB to scheduler cache.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**: None
**Release note**:
```release-note
Add PodDisruptionBudget to scheduler cache.
```
ref/ #53913
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Make scheduler integration test faster
Not to wait for 30 seconds for every negative test case. This commit
also organizes the test code to make it more readable.
It cuts the test time from 450s to 125s.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#53302
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
Previously, the scheduler created two separate list watchers. This
changes the scheduler to be able to leverage a shared informer, whether
passed in externally or spawned using the new in place method. This
removes the last use of a "special" informer in the codebase.
Allows someone wrapping the scheduler to use a shared informer if they
have more information avaliable.
Where possible, switch the scheduler to use generated listers and
informers. There are still some places where it probably makes more
sense to use one-off reflectors/informers (listing/watching just a
single node, listing/watching scheduled & unscheduled pods using a field
selector).
Automatic merge from submit-queue
replace global registry in apimachinery with global registry in k8s.io/kubernetes
We'd like to remove all globals, but our immediate problem is that a shared registry between k8s.io/kubernetes and k8s.io/client-go doesn't work. Since client-go makes a copy, we can actually keep a global registry with other globals in pkg/api for now.
@kubernetes/sig-api-machinery-misc @lavalamp @smarterclayton @sttts
