[YUNIKORN-674] Fixed admission controller for K8s v. 1.19

[kingamarton]

What is this PR for?

The admission controller failed to start because we failed to generate the certificate.

The error related the cert geneeration is the following one:

no kind "CertificateSigningRequest" is registered for version "certificates.k8s.io/v1" in scheme "k8s.io/kubectl/pkg/scheme/scheme.go:28"
Upgrading kubectl to 1.19 will solve the issue for 1.19 version.

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/browse/YUNIKORN-674

How should this be tested?

• running the e2e tests for both K8s 1.19 and for older versions as well
• manual tests

Screenshots (if appropriate)

Questions:

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

[codecov]

Codecov Report

Merging #273 (2950eac) into master (c47ed51) will increase coverage by 2.17%.
The diff coverage is 68.42%.

@@            Coverage Diff             @@
##           master     #273      +/-   ##
==========================================
+ Coverage   59.75%   61.92%   +2.17%     
==========================================
  Files          35       37       +2     
  Lines        3133     3383     +250     
==========================================
+ Hits         1872     2095     +223     
- Misses       1180     1204      +24     
- Partials       81       84       +3     

Impacted Files	Coverage Δ
pkg/appmgmt/appmgmt_recovery.go	67.50% <0.00%> (-8.18%)	⬇️
pkg/cache/amprotocol_mock.go	0.00% <0.00%> (ø)
pkg/cache/context_recovery.go	45.78% <0.00%> (-0.56%)	⬇️
pkg/cache/nodes.go	79.80% <ø> (ø)
pkg/common/events/recorder_mock.go	0.00% <0.00%> (ø)
pkg/common/resource.go	90.72% <0.00%> (-9.28%)	⬇️
pkg/controller/application/app_controller.go	71.05% <ø> (-0.26%)	⬇️
...missioncontrollers/webhook/admission_controller.go	33.74% <0.00%> (+1.00%)	⬆️
pkg/shim/main.go	0.00% <ø> (ø)
pkg/common/events/recorder.go	33.33% <40.00%> (+3.33%)	⬆️
... and 25 more

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