test: cluster.sh fixes for rotate-certs

[jadarsie]

Reason for Change:

Pushing upstream a few rotate-certs e2e fixes we have in place in our own CI.

Credit Where Due:

Does this change contain code from or inspired by another project?

• No
• Yes

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[codecov]

Codecov Report

Merging #4382 (476b6c7) into master (47c439d) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4382      +/-   ##
==========================================
- Coverage   72.07%   72.04%   -0.03%     
==========================================
  Files         141      141              
  Lines       21640    21631       -9     
==========================================
- Hits        15596    15584      -12     
- Misses       5093     5096       +3     
  Partials      951      951              

Impacted Files	Coverage Δ
cmd/upgrade.go	35.92% <0.00%> (-0.54%)	⬇️
pkg/api/defaults.go	93.14% <0.00%> (-0.31%)	⬇️
pkg/engine/templates_generated.go	43.31% <0.00%> (-0.25%)	⬇️
pkg/api/addons.go	98.01% <0.00%> (-0.03%)	⬇️
pkg/engine/artifacts.go	98.88% <0.00%> (-0.03%)	⬇️
pkg/api/types.go	92.85% <0.00%> (ø)
pkg/api/vlabs/types.go	73.04% <0.00%> (ø)
pkg/api/k8s_versions.go	100.00% <0.00%> (ø)
pkg/api/common/versions.go	96.37% <0.00%> (ø)
pkg/api/converterfromapi.go	95.70% <0.00%> (+<0.01%)	⬆️
... and 3 more

---

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[jackfrancis]

lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis, jadarsie

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