Delete unused code

[liubin]

Thank you for contributing to Harbor!

Comprehensive Summary of your change

func GetRedisOfRegURL is not referenced.

Issue being fixed

Fixes #(issue)

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.

[codecov]

Codecov Report

Merging #19061 (b1f2b3a) into main (f3e4216) will decrease coverage by 0.01%.
Report is 2 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #19061      +/-   ##
==========================================
- Coverage   67.41%   67.41%   -0.01%     
==========================================
  Files         993      993              
  Lines      108896   108894       -2     
  Branches     2751     2751              
==========================================
- Hits        73416    73413       -3     
+ Misses      31533    31532       -1     
- Partials     3947     3949       +2     

Flag	Coverage Δ
unittests	67.41% <ø> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
src/lib/config/systemconfig.go	51.87% <ø> (+0.76%)	⬆️

... and 5 files with indirect coverage changes

[chlins]

lgtm

[wy65701436]

lgtm