fix: redis-cluster unexpected downscaling (#1167)

[xiaozhuang-a]

Description

1. ensure statefulset status is ready before scaling
2. failover command is not effective
3. return directly after failover command

Fixes #1167

Type of change

• Bug fix (non-breaking change which fixes an issue)

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 21 lines in your changes missing coverage. Please review.

Project coverage is 29.92%. Comparing base (60ef5a2) to head (8b86853).
Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/k8sutils/cluster-scaling.go	0.00%	13 Missing ⚠️
...ontrollers/rediscluster/rediscluster_controller.go	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1173      +/-   ##
==========================================
- Coverage   30.20%   29.92%   -0.28%     
==========================================
  Files          55       55              
  Lines        6294     6362      +68     
==========================================
+ Hits         1901     1904       +3     
- Misses       4200     4263      +63     
- Partials      193      195       +2     

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[drivebyer]

lgtm