Generate dynamic k8s client only once

[MathieuCesbron]

Description

We generated a new dynamic k8s client everytime we needed it. Now we use the one that is generated in main.go only.

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.

[codecov]

Codecov Report

Attention: 12 lines in your changes are missing coverage. Please review.

Comparison is base (169194a) 29.89% compared to head (1875c92) 30.11%.

Files	Patch %	Lines
controllers/rediscluster_controller.go	0.00%	5 Missing ⚠️
k8sutils/redis-sentinel.go	60.00%	4 Missing ⚠️
k8sutils/status.go	0.00%	2 Missing ⚠️
controllers/redissentinel_controller.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #752      +/-   ##
==========================================
+ Coverage   29.89%   30.11%   +0.21%     
==========================================
  Files          19       19              
  Lines        3241     3231      -10     
==========================================
+ Hits          969      973       +4     
+ Misses       2233     2218      -15     
- Partials       39       40       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.