fix: sink notfound errors

[zhiying-lin]

What type of PR is this?

/kind bug
/kind cleanup

What this PR does / why we need it:
Change the log level from error to info for notFound error

Which issue(s) this PR fixes:

Requirements:

• run make reviewable for basic local test
• Read and followed fleet-networking's Code of conduct.
• uses conventional commit messages
• includes documentation
• adds unit tests

How has this code been tested

Special notes for your reviewer

[codecov]

Codecov Report

Merging #139 (b5273eb) into main (aa10bf5) will decrease coverage by 0.78%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
- Coverage   78.87%   78.08%   -0.79%     
==========================================
  Files          20       20              
  Lines        2551     2587      +36     
==========================================
+ Hits         2012     2020       +8     
- Misses        426      451      +25     
- Partials      113      116       +3     

Impacted Files	Coverage Δ
pkg/controllers/member/serviceimport/controller.go	68.11% <57.14%> (-1.59%)	⬇️
.../controllers/hub/endpointsliceexport/controller.go	69.77% <66.66%> (+2.22%)	⬆️
...ontrollers/hub/internalserviceimport/controller.go	75.79% <66.66%> (-2.12%)	⬇️
pkg/controllers/hub/serviceimport/controller.go	72.85% <66.66%> (-0.87%)	⬇️
...ntrollers/member/endpointsliceexport/controller.go	80.64% <66.66%> (-2.41%)	⬇️
...ntrollers/member/endpointsliceimport/controller.go	72.82% <66.66%> (-3.97%)	⬇️
...rollers/member/internalserviceimport/controller.go	75.43% <66.66%> (-2.34%)	⬇️
pkg/controllers/multiclusterservice/controller.go	85.52% <66.66%> (-1.56%)	⬇️
...ontrollers/hub/internalserviceexport/controller.go	77.97% <80.00%> (-3.24%)	⬇️
pkg/controllers/member/endpointslice/controller.go	78.41% <80.00%> (+0.96%)	⬆️
... and 14 more

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[michaelawyu]

LGTM :)