[YUNIKORN-1828] unify plugin.yaml with other deployment example files

[steinsgateted]

What is this PR for?

changed items:

• add some description: deployments/scheduler/README.md
• deployments/scheduler/plugin.yaml remove RBAC, health check, load balancing
• remove deployments/scheduler/scheduler-load.yaml
• The load balance part is independent: deployments/scheduler/service.yaml

What type of PR is it?

• - Bug Fix
• - Improvement
• - Feature
• - Documentation
• - Hot Fix
• - Refactoring

Todos

• - Task

What is the Jira issue?

https://issues.apache.org/jira/projects/YUNIKORN/issues/YUNIKORN-1828

How should this be tested?

1 Install kind
2 sudo kubectl create -f yunikorn-rbac.yaml
3 sudo kubectl create configmap yunikorn-configs --from-file=yunikorn-configs.yaml
4 sudo kubectl apply -f plugin.yaml
5 check yunikorn web

Screenshots (if appropriate)

Questions:

• - The licenses files need update.
• - There is breaking changes for older versions.
• - It needs documentation.

[codecov]

Codecov Report

Merging #678 (a40e119) into master (5fe1b95) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #678   +/-   ##
=======================================
  Coverage   71.92%   71.92%           
=======================================
  Files          51       51           
  Lines        8082     8082           
=======================================
  Hits         5813     5813           
  Misses       2073     2073           
  Partials      196      196           

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