Fix the bug where the namespace cannot be deleted

[zhengxiexie]

Fix the bug where the namespace cannot be deleted due to the username of the namespace deletion.
Use global log.

Test Done:
On VC UI, namespace can be created and deleted succesfully.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 27 lines in your changes missing coverage. Please review.

Project coverage is 48.34%. Comparing base (8f0c8e4) to head (f9b19de).

Files with missing lines	Patch %	Lines
pkg/controllers/namespace/namespace_controller.go	0.00%	23 Missing ⚠️
pkg/controllers/subnetset/subnetset_webhook.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           v4.2.0     #800      +/-   ##
==========================================
- Coverage   48.43%   48.34%   -0.09%     
==========================================
  Files          94       94              
  Lines       11940    11962      +22     
==========================================
  Hits         5783     5783              
- Misses       5663     5685      +22     
  Partials      494      494              

Flag	Coverage Δ
unit-tests	48.34% <0.00%> (-0.09%)	⬇️

Files with missing lines	Coverage Δ
pkg/controllers/subnetset/subnetset_webhook.go	0.00% <0.00%> (ø)
pkg/controllers/namespace/namespace_controller.go	15.15% <0.00%> (-2.34%)	⬇️