refactor: replace Split in loops with more efficient SplitSeq

[rustversion]

Comprehensive Summary of your change

strings.SplitSeq (introduced in Go 1.23) returns a lazy sequence (strings.Seq), allowing gopher to iterate over tokens one by one without creating an intermediate slice.

More info: golang/go#61901

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[chlins]

lgtm

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.84%. Comparing base (c8c11b4) to head (ab1a8ac).
⚠️ Report is 580 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #22494       +/-   ##
===========================================
+ Coverage   45.36%   65.84%   +20.47%     
===========================================
  Files         244     1073      +829     
  Lines       13333   116106   +102773     
  Branches     2719     2931      +212     
===========================================
+ Hits         6049    76446    +70397     
- Misses       6983    35423    +28440     
- Partials      301     4237     +3936     

Flag	Coverage Δ
unittests	65.84% <100.00%> (+20.47%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/controller/registry/controller.go	29.52% <100.00%> (ø)

... and 986 files with indirect coverage changes

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[wy65701436]

lgtm