feat: rolling update sequence from leader to follower

[drivebyer]

Description

Fixes #951

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• Tests have been added/modified and all tests pass.
• Functionality/bugs have been confirmed to be unchanged or fixed.
• I have performed a self-review of my own code.
• Documentation has been updated or added where necessary.

Additional Context

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 33 lines in your changes missing coverage. Please review.

Project coverage is 40.69%. Comparing base (d121d86) to head (e89777d).
Report is 65 commits behind head on master.

❗ Current head e89777d differs from pull request most recent head 9125951

Please upload reports for the commit 9125951 to get more accurate results.

Files	Patch %	Lines
k8sutils/statefulset.go	0.00%	29 Missing ⚠️
controllers/rediscluster_controller.go	0.00%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #966      +/-   ##
==========================================
+ Coverage   35.20%   40.69%   +5.49%     
==========================================
  Files          19       20       +1     
  Lines        3213     2703     -510     
==========================================
- Hits         1131     1100      -31     
+ Misses       2015     1532     -483     
- Partials       67       71       +4     

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[wkd-woo]

Great !