Add exlude namespace predicate

[dnugmanov]

What this PR does:
Add a predicate function that will exclude specified namespaces from reconciliation, through the env variable

Which issue(s) this PR fixes:
Fixes #1035

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CHANGELOG.md updated (not required for documentation PRs)
• CLA Signed: DataStax CLA

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
17.1% Duplication

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[codecov]

Codecov Report

Merging #1041 (e1b0084) into main (6099857) will decrease coverage by 0.03%.
The diff coverage is 90.00%.

@@            Coverage Diff             @@
##             main    #1041      +/-   ##
==========================================
- Coverage   57.43%   57.40%   -0.03%     
==========================================
  Files         100      100              
  Lines       10045    10045              
==========================================
- Hits         5769     5766       -3     
- Misses       3783     3785       +2     
- Partials      493      494       +1     

Files Changed	Coverage Δ
...trollers/medusa/medusabackupschedule_controller.go	73.23% <0.00%> (ø)
controllers/config/clientconfig_controller.go	82.48% <100.00%> (ø)
controllers/control/k8ssandratask_controller.go	64.00% <100.00%> (ø)
...ntrollers/k8ssandra/k8ssandracluster_controller.go	75.00% <100.00%> (ø)
controllers/medusa/medusabackupjob_controller.go	58.13% <100.00%> (ø)
controllers/medusa/medusarestorejob_controller.go	56.61% <100.00%> (ø)
controllers/medusa/medusatask_controller.go	48.12% <100.00%> (ø)
controllers/reaper/reaper_controller.go	52.36% <100.00%> (ø)
controllers/replication/secret_controller.go	65.43% <100.00%> (+1.00%)	⬆️
controllers/stargate/stargate_controller.go	46.55% <100.00%> (ø)

... and 2 files with indirect coverage changes