feat(rdb): make upgrade/database/user create idempotent with no-op success messages

[jremy42]

close #4301

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Relates OR Closes #0000

Release note for CHANGELOG:

[codecov-commenter]

Codecov Report

❌ Patch coverage is 62.85714% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.42%. Comparing base (7a6ff47) to head (623fd53).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
internal/namespaces/rdb/v1/custom_instance.go	47.05%	15 Missing and 3 partials ⚠️
internal/namespaces/rdb/v1/custom_user.go	72.22%	4 Missing and 1 partial ⚠️
internal/namespaces/rdb/v1/custom_database.go	81.25%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5097      +/-   ##
==========================================
- Coverage   57.43%   57.42%   -0.01%     
==========================================
  Files         308      309       +1     
  Lines       67218    67263      +45     
==========================================
+ Hits        38608    38629      +21     
- Misses      27173    27193      +20     
- Partials     1437     1441       +4     

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